How memory works

Grey Matter

Older news items (pre-2010) brought over from the old website

Healthy older brains not significantly smaller than younger brains

A study using healthy older adults from Holland's long-term Maastricht Aging Study found that the 35 cognitively healthy people who stayed free of dementia showed no significant decline in gray matter, but the 30 people who showed substantial cognitive decline although still dementia-free showed a significant reduction in brain tissue in the hippocampus and parahippocampal areas, and in the frontal and cingulate cortices. The findings suggest that atrophy in the normal older brain may have been over-estimated in earlier studies, by not screening out people whose undetected, slowly developing brain disease was killing off cells in key areas.

[1151] Burgmans, S., van Boxtel M. P. J., Vuurman E. F. P. M., Smeets F., Gronenschild E. H. B. M., Uylings H. B. M., et al.
(2009).  The prevalence of cortical gray matter atrophy may be overestimated in the healthy aging brain.
Neuropsychology. 23(5), 541 - 550.

http://www.eurekalert.org/pub_releases/2009-09/apa-hob090309.php

Learning to juggle grows white matter

A study in which 24 young adults practiced juggling for half an hour a day for six weeks found that they grew more white matter in the area underlying the intraparietal sulcus. This occurred in all the jugglers, regardless of skill, suggesting it's the learning process itself that is important. Previous research has found that juggling increases grey matter. After four weeks without juggling, the new white matter remained and the amount of grey matter had even increased.

[241] Scholz, J., Klein M. C., Behrens T. E. J., & Johansen-Berg H.
(2009).  Training induces changes in white-matter architecture.
Nat Neurosci. 12(11), 1370 - 1371.

http://www.newscientist.com/article/dn17957-learning-to-juggle-grows-brain-networks-for-good.html

Tetris increases gray matter and improves brain efficiency

In a study in which 26 adolescent girls played the computer game Tetris for half an hour every day for three months, their brains compared to controls increased grey matter in Brodmann Area 6 in the left frontal lobe and BAs 22 and 38 in the left temporal lobe — areas involved in planning complex coordinated movements, and coordinating sensory information. Their brains also showed greater efficiency, but in different areas — ones associated with critical thinking, reasoning, and language, mostly in the right frontal and parietal lobes. The finding points to improved efficiency being unrelated to grey matter increases.

[600] Haier, R. J., Karama S., Leyba L., & Jung R.
(2009).  MRI assessment of cortical thickness and functional activity changes in adolescent girls following three months of practice on a visual-spatial task.
BMC Research Notes. 2(1), 174 - 174.

http://www.eurekalert.org/pub_releases/2009-09/bc-itg090109.php

Neural changes produced by learning to read revealed

Understanding how our brain structures change as we learn to read is difficult because of the confounding with age and the learning of other skills. Studying adult learners is also problematic because in most educated societies adult illiteracy is typically the result of learning impairments or poor health. Now a new study involving 20 former guerrillas in Colombia who are learning to read for the first time as adults has found that these late-literates showed a number of significant brain differences compared to matched adult illiterates, including more white matter between various regions, and more grey matter in various left temporal and occipital regions important for recognizing letter shapes and translating letters into speech sounds and their meanings. Particularly important were connections between the left and right angular gyri in the parietal lobe. While this area has long been known as important for reading, its function turns out to have been misinterpreted — it now appears its main role is in anticipating what we will see. The findings will help in understanding the causes of dyslexia.

[267] Carreiras, M., Seghier M. L., Baquero S., Estevez A., Lozano A., Devlin J. T., et al.
(2009).  An anatomical signature for literacy.
Nature. 461(7266), 983 - 986.

http://www.physorg.com/news174744233.html

Changes in gray matter induced by learning

Three months of training in three-ball cascade juggling was found to be associated with a transient and highly selective increase in gray matter in the occipito-temporal cortex. A follow-up study involving 20 adults confirmed this finding and found that the change in grey matter occurred after only 7 days of training. Neither performance nor exercise alone could explain these changes, and the increase receded when training stopped. The researchers suggest that learning a new task is more critical for the brain to change its structure than continued training of an already-learned task.

[1412] Driemeyer, J., Boyke J., Gaser C., Büchel C., & May A.
(2008).  Changes in Gray Matter Induced by Learning—Revisited.
PLoS ONE. 3(7), e2669 - e2669.

http://www.plosone.org/article/info:doi/10.1371/journal.pone.0002669

Neural substrate of congenital amusia

Research has shown that musicians have more gray matter in certain regions of the brain involved in language and auditory processing. Now a study of tone-deaf people reveals that congenital amusia, thought to be due to a severe deficit in the processing of pitch information, is also associated with differences in gray matter distribution. Tone-deaf individuals had a thicker cortex in the right inferior frontal gyrus and right auditory cortex. This may be due to abnormal neuronal migration or atypical cell pruning during development.

Hyde, K.L. et al. 2007. Cortical Thickness in Congenital Amusia: When Less Is Better Than More. The Journal of Neuroscience, 27(47), 13028-13032.

http://www.physorg.com/news117303842.html

IQ-related brain areas may differ in men and women

An imaging study of 48 men and women between 18 and 84 years old found that, although men and women performed equally on the IQ tests, the brain structures involved in intelligence appeared distinct. Compared with women, men had more than six times the amount of intelligence-related gray matter, while women had about nine times more white matter involved in intelligence than men did. Women also had a large proportion of their IQ-related brain matter (86% of white and 84% of gray) concentrated in the frontal lobes, while men had 90% of their IQ-related gray matter distributed equally between the frontal lobes and the parietal lobes, and 82% of their IQ-related white matter in the temporal lobes. The implications of all this are not clear, but it is worth noting that the volume of gray matter can increase with learning, and is thus a product of environment as well as genes. The findings also demonstrate that no single neuroanatomical structure determines general intelligence and that different types of brain designs are capable of producing equivalent intellectual performance.

[938] Haier, R. J., Jung R. E., Yeo R. A., Head K., & Alkire M. T.
(2005).  The neuroanatomy of general intelligence: sex matters.
NeuroImage. 25(1), 320 - 327.

http://www.eurekalert.org/pub_releases/2005-01/uoc--iim012005.php
http://www.sciencedaily.com/releases/2005/01/050121100142.htm

Chronic back pain shrinks 'thinking parts' of the brain

A new study has found chronic back pain shrinks the brain by as much as 11% — equivalent to the amount of gray matter lost in 10 to 20 years of normal aging. Loss in brain density is related to pain duration, indicating that 1.3 cubic centimeters of gray matter are lost for every year of chronic pain. The study compared 26 participants with chronic back pain for more than a year with matched normal subjects.

Apkarian, A.V., Sosa, Y., Sonty, S., Levy, R.M., Harden, R.N., Parrish, T.B. & Gitelman, D.R. 2004. Chronic Back Pain Is Associated with Decreased Prefrontal and Thalamic Gray Matter Density. Journal of Neuroscience, 24, 10410-10415.

http://www.eurekalert.org/pub_releases/2004-11/nu-cbp111504.php

Learning languages increases gray matter density

An imaging study of 25 Britons who did not speak a second language, 25 people who had learned another European language before the age of five and 33 bilinguals who had learned a second language between 10 and 15 years old found that the density of the gray matter in the left inferior parietal cortex of the brain was greater in bilinguals than in those without a second language. The effect was particularly noticeable in the "early" bilinguals. The findings were replicated in a study of 22 native Italian speakers who had learned English as a second language between the ages of two and 34.

Mechelli, A., Crinion, J.T., Noppeney, U., O'doherty, J., Ashburner, J., Frackowiak, R.S. & Price, C.J. 2004. Neurolinguistics: Structural plasticity in the bilingual brain. Nature, 431, 757.

http://news.bbc.co.uk/2/hi/health/3739690.stm

Intelligence based on the volume of gray matter in certain brain regions

Confirming earlier suggestions, the most comprehensive structural brain-scan study of intelligence to date supports an association between general intelligence and the volume of gray matter tissue in certain regions of the brain. Because these regions are located throughout the brain, a single "intelligence center" is unlikely. It is likely that a person's mental strengths and weaknesses depend in large part on the individual pattern of gray matter across his or her brain. Although gray matter amounts are vital to intelligence levels, only about 6% of the brain’s gray matter appears related to IQ — intelligence seems related to an efficient use of relatively few structures. The structures that are important for intelligence are the same ones implicated in memory, attention and language. There are also age differences: in middle age, more of the frontal and parietal lobes are related to IQ; less frontal and more temporal areas are related to IQ in the younger adults. Previous research has shown the regional distribution of gray matter in humans is highly heritable. The findings also challenge the recent view that intelligence may be a reflection of more subtle characteristics of the brain, such as the speed at which nerve impulses travel in the brain, or the number of neuronal connections present. It may of course be that all of these are factors.

[715] Haier, R. J., Jung R. E., Yeo R. A., Head K., & Alkire M. T.
(2004).  Structural brain variation and general intelligence.
NeuroImage. 23(1), 425 - 433.

http://www.sciencedaily.com/releases/2004/07/040720090419.htm
http://www.eurekalert.org/pub_releases/2004-07/uoc--hid071904.php

Growing evidence cerebellum involved in language

An imaging study of children with selective problems in short term phonological memory and others diagnosed with specific language impairment (and matched controls) found that those with selective STPM deficits and those with SLI had less gray matter in both sides of the cerebellum compared to the children in the control groups. This supports growing evidence that the cerebellum, an area of the brain once thought to be involved only in the control of movement, also plays a role in processing speech and language.

http://www.eurekalert.org/pub_releases/2003-11/sfn-ssb111103.php

Maturation of the human brain mapped

The progressive maturation of the human brain in childhood and adolescence has now been mapped. The initial overproduction of synapses in the gray matter that occurs after birth, is followed, for the most part just before puberty, with their systematic pruning. The mapping has confirmed that this maturation process occurs in different regions at different times, and has found that the normal gray matter loss begins first in the motor and sensory parts of the brain, and then slowly spreads downwards and forwards, to areas involved in spatial orientation, speech and language development, and attention (upper and lower parietal lobes), then to the areas involved in executive functioning, attention or motor coordination (frontal lobes), and finally to the areas that integrate these functions (temporal lobe). "The surprising thing is that the sequence in which the cortex matures appears to agree with regionally relevant milestones in cognitive development, and also reflects the evolutionary sequence in which brain regions were formed."

http://www.eurekalert.org/pub_releases/2003-11/sfn-smm110803.php

Imaging study confirms link between exercise and cognitive function

A number of studies have suggested a link between exercise and cognitive function in older adults, but now an imaging study shows that there are actual anatomical differences in the brains of physically fit versus less fit older adults (over 55). Specifically, they found very distinct differences in the gray and white matter in the frontal, temporal, and parietal cortexes. With aging, these tissues shrink, a reduction closely matched by declines in cognitive performance. Fitness, it appears, slows that decline. A related study, published in March, suggests that women may benefit more from exercise than men.

Colcombe, S.J., Erickson, K.I., Raz, N., Webb, A.G., Cohen, N.J., McAuley, E. & Kramer, A.F. 2003. Aerobic Fitness Reduces Brain Tissue Loss in Aging Humans. Journal of Gerontology: Series A: Biological and Medical Sciences, 58, M176-M180.

http://www.eurekalert.org/pub_releases/2003-01/uoia-sif012703.php

More grey matter in the auditory cortex of musicians' brains

New research augments earlier findings concerning the amount and distribution of gray matter in the brains of professional musicians. It now appears that musicians also have an increased volume of grey matter in the Broca's area, an area of the brain involved in the production of language. A critical factor appears to be the number of years devoted to musical training - at least for musicians under the age of 50. The research supports recent suggestions that musicians process music like an additional language.

Sluming, V., Barrick, T., Howard, M., Cezayirli, E., Mayes, A. & Roberts, N. 2002. Voxel-Based Morphometry Reveals Increased Gray Matter Density in Broca's Area in Male Symphony Orchestra Musicians, NeuroImage, 17(3), 1613-1622.

Significant brain differences between professional musicians trained at an early age and non-musicians

Research has revealed significant differences in the gray matter distribution between professional musicians trained at an early age and non-musicians. It is most likely that this is due to intensive musical training at an early age, although it is also possible that the musicians were born with these differences, which led them to pursue musical training.

Schlaug, G. & Christian, G. Paper presented May 7 at the American Academy of Neurology's 53rd Annual Meeting in Philadelphia, PA.

http://www.eurekalert.org/pub_releases/2001-05/AAoN-Mtdc-0705101.php

Calculation difficulties in children of very low birthweight

Learning difficulties, including problems with numeracy, are common in Western populations. Many children with learning difficulty are survivors of preterm birth. Although some of these children have neurological disabilities, many are neurologically normal. A neuroimaging study of neurologically normal adolescent children who had been born preterm at 30 weeks gestation or less found an area in the left parietal lobe where children without a deficit in calculation ability have more grey matter than those who do have this deficit.

Isaacs, E.B., Edmonds, C.J., Lucas, A. & Gadian, D.G. (2001). Calculation difficulties in children of very low birthweight: A neural correlate. Brain, 124 (9, 1701-1707.

http://news.bbc.co.uk/hi/english/sci/tech/newsid_1512000/1512664.stm

Gray matter may decline from adolescence, but white matter keeps growing until our late forties

Brain scans of 70 men, ages 19 to 76 confirms that the brain's gray matter, the cell bodies of nerve cells, declines steadily from adolescence. But surprisingly, the white matter, the fatty material that insulates the long extending branches of the nerve cells and makes nerve signals move faster, in the frontal parts of the brain appears to grow at least until the late 40's, before beginning to decline. The growth of white matter may improve the brain's ability to process information.

Bartzokis, G., Beckson, M., Lu, P.H., Nuechterlein, K.H., Edwards, N. & Mintz, J. 2001. Age-Related Changes in Frontal and Temporal Lobe Volumes in Men: A Magnetic Resonance Imaging Study. Archives of General Psychiatry, 58, 461-465.

http://www.nytimes.com/2001/05/22/health/22VITA-3.html

Mental faculties unchanged until the mid-40s

A large-scale study of mental abilities in adults found that mental faculties were unchanged until the mid-40s, when a marked decline began and continued at a constant rate. The ability to remember words after a delay was especially affected. Accuracy did not seem to be affected, only speed.

The paper was presented to a British Psychological Society conference in London.

http://www.guardian.co.uk/Archive/Article/0,4273,4108165,00.html

Working Memory

Older news items (pre-2010) brought over from the old website

More light shed on distinction between long and short-term memory

The once clear-cut distinction between long- and short-term memory has increasingly come under fire in recent years. A new study involving patients with a specific form of epilepsy called 'temporal lobe epilepsy with bilateral hippocampal sclerosis' has now clarified the distinction. The patients, who all had severely compromised hippocampi, were asked to try and memorize photographic images depicting normal scenes. Their memory was tested and brain activity recorded after five seconds or 60 minutes. As expected, the patients could not remember the images after 60 minutes, but could distinguish seen-before images from new at five seconds. However, their memory was poor when asked to recall details about the images. Brain activity showed that short-term memory for details required the coordinated activity of a network of visual and temporal brain areas, whereas standard short-term memory drew on a different network, involving frontal and parietal regions, and independent of the hippocampus.

[996] Cashdollar, N., Malecki U., Rugg-Gunn F. J., Duncan J. S., Lavie N., & Duzel E.
(2009).  Hippocampus-dependent and -independent theta-networks of active maintenance.
Proceedings of the National Academy of Sciences. 106(48), 20493 - 20498.

http://www.eurekalert.org/pub_releases/2009-11/ucl-tal110909.php

Short stressful events may improve working memory

We know that chronic stress has a detrimental effect on learning and memory, but a new rat study shows how acute stress (a short, sharp event) can produce a beneficial effect. The rats, trained to a level of 60-70% accuracy on a maze, were put through a 20-minute forced swim before being run through the maze again. Those who experienced this stressful event were better at running the maze 4 hours later, and a day later, than those not forced through the stressful event. It appears that the stress hormone corticosterone (cortisol in humans) increases transmission of the neurotransmitter glutamate in the prefrontal cortex and improves working memory. It also appears that chronic stress suppresses the transmission of glutamate in the prefrontal cortex of male rodents, while estrogen receptors in female rodents make them more resilient to chronic stress than male rats.

[1157] Yuen, E. Y., Liu W., Karatsoreos I. N., Feng J., McEwen B. S., & Yan Z.
(2009).  Acute stress enhances glutamatergic transmission in prefrontal cortex and facilitates working memory.
Proceedings of the National Academy of Sciences of the United States of America. 106(33), 14075 - 14079.

http://www.eurekalert.org/pub_releases/2009-07/uab-sse072309.php

Individual differences in working memory capacity depend on two factors

A new computer model adds to our understanding of working memory, by showing that working memory can be increased by the action of the prefrontal cortex in reinforcing activity in the parietal cortex (where the information is temporarily stored). The idea is that the prefrontal cortex sends out a brief stimulus to the parietal cortex that generates a reverberating activation in a small subpopulation of neurons, while inhibitory interactions with neurons further away prevents activation of the entire network. This lateral inhibition is also responsible for limiting the mnemonic capacity of the parietal network (i.e. provides the limit on your working memory capacity). The model has received confirmatory evidence from an imaging study involving 25 volunteers. It was found that individual differences in performance on a short-term visual memory task were correlated with the degree to which the dorsolateral prefrontal cortex was activated and its interconnection with the parietal cortex. In other words, your working memory capacity is determined by both storage capacity (in the posterior parietal cortex) and prefrontal top-down control. The findings may help in the development of ways to improve working memory capacity, particularly when working memory is damaged.

[441] Edin, F., Klingberg T., Johansson P., McNab F., Tegner J., & Compte A.
(2009).  Mechanism for top-down control of working memory capacity.
Proceedings of the National Academy of Sciences. 106(16), 6802 - 6807.

http://www.eurekalert.org/pub_releases/2009-04/i-id-aot040109.php

Some short-term memories die suddenly, no fading

We don’t remember everything; the idea of memory as being a video faithfully recording every aspect of everything we have ever experienced is a myth. Every day we look at the world and hold a lot of what we say for no more than a few seconds before discarding it as not needed any more. Until now it was thought that these fleeting visual memories faded away, gradually becoming more imprecise. Now it seems that such memories remain quite accurate as long as they exist (about 4 seconds), and then just vanish away instantly. The study involved testing memory for shapes and colors in 12 adults, and it was found that the memory for shape or color was either there or not there – the answers either correct or random guesses. The probability of remembering correctly decreased between 4 and 10 seconds.

[941] Zhang, W., & Luck S. J.
(2009).  Sudden death and gradual decay in visual working memory.
Psychological Science: A Journal of the American Psychological Society / APS. 20(4), 423 - 428.

http://www.eurekalert.org/pub_releases/2009-04/uoc--ssm042809.php

Where visual short-term memory occurs

Working memory used to be thought of as a separate ‘store’, and now tends to be regarded more as a process, a state of mind. Such a conception suggests that it may occur in the same regions of the brain as long-term memory, but in a pattern of activity that is somehow different from LTM. However, there has been little evidence for that so far. Now a new study has found that information in WM may indeed be stored via sustained, but low, activity in sensory areas. The study involved volunteers being shown an image for one second and instructed to remember either the color or the orientation of the image. After then looking at a blank screen for 10 seconds, they were shown another image and asked whether it was the identical color/orientation as the first image. Brain activity in the primary visual cortex was scanned during the 10 second delay, revealing that areas normally involved in processing color and orientation were active during that time, and that the pattern only contained the targeted information (color or orientation).

[1032] Serences, J. T., Ester E. F., Vogel E. K., & Awh E.
(2009).  Stimulus-Specific Delay Activity in Human Primary Visual Cortex.
Psychological Science. 20(2), 207 - 214.

http://www.eurekalert.org/pub_releases/2009-02/afps-sih022009.php
http://www.eurekalert.org/pub_releases/2009-02/uoo-dsm022009.php

The finding is consistent with that of another study published this month, in which participants were shown two examples of simple striped patterns at different orientations and told to hold either one or the other of the orientations in their mind while being scanned. Orientation is one of the first and most basic pieces of visual information coded and processed by the brain. Using a new decoding technique, researchers were able to predict with 80% accuracy which of the two orientations was being remembered 11 seconds after seeing a stimulus, from the activity patterns in the visual areas. This was true even when the overall level of activity in these visual areas was very weak, no different than looking at a blank screen.

[652] Harrison, S. A., & Tong F.
(2009).  Decoding reveals the contents of visual working memory in early visual areas.
Nature. 458(7238), 632 - 635.

http://www.eurekalert.org/pub_releases/2009-02/vu-edi021709.php
http://www.physorg.com/news154186809.html

Even toddlers can ‘chunk' information for better remembering

We all know it’s easier to remember a long number (say a phone number) when it’s broken into chunks. Now a study has found that we don’t need to be taught this; it appears to come naturally to us. The study showed 14 months old children could track only three hidden objects at once, in the absence of any grouping cues, demonstrating the standard limit of working memory. However, with categorical or spatial cues, the children could remember more. For example, when four toys consisted of two groups of two familiar objects, cats and cars, or when six identical orange balls were grouped in three groups of two.

Feigenson, L. & Halberda, J. 2008. Conceptual knowledge increases infants' memory capacity. Proceedings of the National Academy of Sciences, 105 (29), 9926-9930.

http://www.eurekalert.org/pub_releases/2008-07/jhu-etg071008.php

Full text available at http://www.pnas.org/content/105/29/9926.abstract?sid=c01302b6-cd8e-4072-842c-7c6fcd40706f

Brain-training to improve working memory boosts fluid intelligence

General intelligence is often separated into "fluid" and "crystalline" components, of which fluid intelligence is considered more reflective of “pure” intelligence, and largely resistant to training and learning effects. However, in a new study in which participants were given a series of training exercises designed to improve their working memory, fluid intelligence was found to have significantly improved, with the amount of improvement increasing with time spent training. The small study contradicts decades of research showing that improving on one kind of cognitive task does not improve performance on other kinds, so has been regarded with some skepticism by other researchers. More research is definitely needed, but the memory task did differ from previous studies, engaging executive functions such as those that inhibit irrelevant items, monitor performance, manage two tasks simultaneously, and update memory.

Jaeggi, S.M., Buschkuehl, M., Jonides, J. & Perrig, W.J. 2008. Improving fluid intelligence with training on working memory. PNAS, 105 (19), 6829-6833.

http://www.physorg.com/news128699895.html
http://www.sciam.com/article.cfm?id=study-shows-brain-power-can-be-bolstered

Working memory has a fixed number of 'slots'

A study that showed volunteers a pattern of colored squares for a tenth of a second, and then asked them to recall the color of one of the squares by clicking on a color wheel, has found that working memory acts like a high-resolution camera, retaining three or four features in high detail. Unlike a digital camera, however, it appears that you can’t increase the number of images you can store by lowering the resolution. The resolution appears to be constant for a given individual. However, individuals do differ in the resolution of each feature and the number of features that can be stored.

[278] Zhang, W., & Luck S. J.
(2008).  Discrete fixed-resolution representations in visual working memory.
Nature. 453(7192), 233 - 235.

http://www.physorg.com/news126432902.html
http://www.eurekalert.org/pub_releases/2008-04/uoc--wmh040208.php

And another study of working memory has attempted to overcome the difficulties involved in measuring a person’s working memory capacity (ensuring that no ‘chunking’ of information takes place), and concluded that people do indeed have a fixed number of ‘slots’ in their working memory. In the study, participants were shown two, five or eight small, scattered, different-colored squares in an array, which was then replaced by an array of the same squares without the colors, after which the participant was shown a single color in one location and asked to indicate whether the color in that spot had changed from the original array.

[437] Rouder, J. N., Morey R. D., Cowan N., Zwilling C. E., Morey C. C., & Pratte M. S.
(2008).  An assessment of fixed-capacity models of visual working memory.
Proceedings of the National Academy of Sciences. 105(16), 5975 - 5979.

http://www.eurekalert.org/pub_releases/2008-04/uom-mpd042308.php

Impressive feats in visual memory

In light of all the recent experiments emphasizing how small our short-term visual memory is, it’s comforting to be reminded that, nevertheless, we have an amazing memory for pictures — in the right circumstances. Those circumstances include looking at images of familiar objects, as opposed to abstract artworks, and being motivated to do well (the best-scoring participant was given a cash prize). In the study, 14 people aged 18 to 40 viewed 2,500 images, one at a time, for a few seconds. Afterwards, they were shown pairs of images and asked to select the exact image they had seen earlier. The previously viewed item could be paired with either an object from a novel category, an object of the same basic-level category, or the same object in a different state or pose. Stunningly, participants on average chose the correct image 92%, 88% and 87% of the time, in each of the three pairing categories respectively.

[870] Brady, T. F., Konkle T., Alvarez G. A., & Oliva A.
(2008).  Visual long-term memory has a massive storage capacity for object details.
Proceedings of the National Academy of Sciences. 105(38), 14325 - 14329.

Full text available at http://www.pnas.org/content/105/38/14325.abstract

Children's under-achievement could be down to poor working memory

A survey of over three thousand children has found that 10% of school children across all age ranges suffer from poor working memory seriously affecting their learning. However, poor working memory is rarely identified by teachers, who often describe children with this problem as inattentive or as having lower levels of intelligence. The researchers have developed a new tool, a combination of a checklist and computer programme called the Working Memory Rating Scale, that enables teachers to identify and assess children's memory capacity in the classroom from as early as four years old. The tool has already been piloted successfully in 35 schools across the UK, and is now widely available. It has been translated into ten foreign languages.

http://www.physorg.com/news123404466.html 
http://www.eurekalert.org/pub_releases/2008-02/du-cuc022608.php

More on how short-term memory works

It’s been established that visual working memory is severely limited — that, on average, we can only be aware of about four objects at one time. A new study explored the idea that this capacity might be affected by complexity, that is, that we can think about fewer complex objects than simple objects. It found that complexity did not affect memory capacity. It also found that some people have clearer memories of the objects than other people, and that this is not related to how many items they can remember. That is, a high IQ is associated with the ability to hold more items in working memory, but not with the clarity of those items.

[426] Awh, E., Barton B., & Vogel E. K.
(2007).  Visual working memory represents a fixed number of items regardless of complexity.
Psychological Science: A Journal of the American Psychological Society / APS. 18(7), 622 - 628.

http://www.eurekalert.org/pub_releases/2007-07/uoo-htb071107.php
http://www.physorg.com/news103472118.html

Executive function as important as IQ for math success

A study of 141 preschoolers from low-income homes has found that a child whose IQ and executive functioning were both above average was three times more likely to succeed in math than a child who simply had a high IQ. The parts of executive function that appear to be particularly linked to math ability in preschoolers are working memory and inhibitory control. In this context, working memory may be thought of as the ability to keep information or rules in mind while performing mental tasks. Inhibitory control is the ability to halt automatic impulses and focus on the problem at hand. Inhibitory control was also important for reading ability. The finding offers the hope that training to improve executive function will improve academic performance

Blair, C. & Razza, R.P. 2007. Relating Effortful Control, Executive Function, and False Belief Understanding to Emerging Math and Literacy Ability in Kindergarten. Child Development, 78 (2), 647–663.

New research shows why too much memory may be a bad thing

People who are able to easily and accurately recall historical dates or long-ago events may have a harder time with word recall or remembering the day's current events. A mouse study reveals why. Neurogenesis has been thought of as a wholly good thing — having more neurons is surely a good thing — but now a mouse study has found that stopping neurogenesis in the hippocampus improved working memory. Working memory is highly sensitive to interference from information previously stored in memory, so it may be that having too much information may hinder performing everyday working memory tasks.

Saxe, M.D. et al. 2007. Paradoxical influence of hippocampal neurogenesis on working memory. Proceedings of the National Academy of Sciences, 104 (11), 4642-4646.

http://www.physorg.com/news94384934.html
http://www.eurekalert.org/pub_releases/2007-03/cumc-nrs032807.php

Implicit stereotypes and gender identification may affect female math performance

Relatedly, another study has come out showing that women enrolled in an introductory calculus course who possessed strong implicit gender stereotypes, (for example, automatically associating "male" more than "female" with math ability and math professions) and were likely to identify themselves as feminine, performed worse relative to their female counterparts who did not possess such stereotypes and who were less likely to identify with traditionally female characteristics. Strikingly, a majority of the women participating in the study explicitly expressed disagreement with the idea that men have superior math ability, suggesting that even when consciously disavowing stereotypes, female math students are still susceptible to negative perceptions of their ability.

Kiefer, A.K., & Sekaquaptewa, D. 2007. Implicit stereotypes, gender identification, and math performance: a prospective study of female math students. Psychological Science, 18(1), 13-18.

http://www.eurekalert.org/pub_releases/2007-01/afps-isa012407.php

Reducing the racial achievement gap

And staying with the same theme, a study that came out six months ago, and recently reviewed on the excellent new Scientific American Mind Matters blog, revealed that a single, 15-minute intervention erased almost half the racial achievement gap between African American and white students. The intervention involved writing a brief paragraph about which value, from a list of values, was most important to them and why. The intervention improved subsequent academic performance for some 70% of the African American students, but none of the Caucasians. The study was repeated the following year with the same results. It is thought that the effect of the intervention was to protect against the negative stereotypes regarding the intelligence and academic capabilities of African Americans.

[1082] Cohen, G. L., Garcia J., Apfel N., & Master A.
(2006).  Reducing the Racial Achievement Gap: A Social-Psychological Intervention.
Science. 313(5791), 1307 - 1310.

Highly accomplished people more prone to failure than others when under stress

One important difference between those who do well academically and those who don’t is often working memory capacity. Those with a high working memory capacity find it easier to read and understand and reason, than those with a smaller capacity. However, a new study suggests there is a downside. Such people tend to heavily rely on their abundant supply of working memory and are therefore disadvantaged when challenged to solve difficult problems, such as mathematical ones, under pressure — because the distraction caused by stress consumes their working memory. They then fall back on the less accurate short-cuts that people with less adequate supplies of working memory tend to use, such as guessing and estimation. Such methods are not made any worse by working under pressure. In the study involving 100 undergraduates, performance of students with strong working memory declined to the same level as those with more limited working memory, when the students were put under pressure. Those with more limited working memory performed as well under added pressure as they did without the stress.

The findings were presented February 17 at the annual meeting of the American Association for the Advancement of Science.

http://www.eurekalert.org/pub_releases/2007-02/uoc-hap021607.php

Common gene version optimizes thinking but carries a risk

On the same subject, another study has found that the most common version of DARPP-32, a gene that shapes and controls a circuit between the striatum and prefrontal cortex, optimizes information filtering by the prefrontal cortex, thus improving working memory capacity and executive control (and thus, intelligence). However, the same version was also more prevalent among people who developed schizophrenia, suggesting that a beneficial gene variant may translate into a disadvantage if the prefrontal cortex is impaired. In other words, one of the things that make humans more intelligent as a species may also make us more vulnerable to schizophrenia.

[864] Kolachana, B., Kleinman J. E., Weinberger D. R., Meyer-Lindenberg A., Straub R. E., Lipska B. K., et al.
(2007).  Genetic evidence implicating DARPP-32 in human frontostriatal structure, function, and cognition.
Journal of Clinical Investigation. 117(3), 672 - 682.

http://www.sciencedaily.com/releases/2007/02/070208230059.htm
http://www.eurekalert.org/pub_releases/2007-02/niom-cgv020707.php

People remember prices more easily if they have fewer syllables

The phonological loop — an important component of working memory —can only hold 1.5 to 2 seconds of spoken information. For that reason, faster speakers have an advantage over slower speakers. Now a consumer study reveals that every extra syllable in a product's price decreases its chances of being remembered by 20%. Thus, people who shorten the number of syllables (e.g. read 5,325 as 'five three two five' as opposed to 'five thousand three hundred and twenty five') have better recall. However, since we store information both verbally and visually, it’s also the case that unusual looking prices, such as $8.88, are recalled better than typical looking prices.

Vanhuele, M., Laurent, G., Dreze, X. & Calder, B. 2006. Consumers' Immediate Memory for Prices. Journal of Consumer Research, 33(2), 163-72.

http://www.sciencedaily.com/releases/2006/06/060623001231.htm
http://www.eurekalert.org/pub_releases/2006-06/uocp-prp062206.php

New view of hippocampus’s role in memory

Amnesiacs have overturned the established view of the hippocampus, and of the difference between long-and short-term memories. It appears the hippocampus is just as important for retrieving certain types of short-term memories as it is for long-term memories. The critical thing is not the age of the memory, but the requirement to form connections between pieces of information to create a coherent episode. The researchers suggest that, for the brain, the distinction between 'long-term' memory and 'short-term' memory are less relevant than that between ‘feature’ memory and ‘conjunction’ memory — the ability to remember specific things versus how they are related. The hippocampus may be thought of as the brain's switchboard, piecing individual bits of information together in context.

[817] Olson, I. R., Page K., Moore K S., Chatterjee A., & Verfaellie M.
(2006).  Working Memory for Conjunctions Relies on the Medial Temporal Lobe.
J. Neurosci.. 26(17), 4596 - 4601.

http://origin.www.upenn.edu/pennnews/article.htm?id=963
http://www.eurekalert.org/pub_releases/2006-05/uop-aso053106.php

Learning and working memory

A 3-year research project on Working Memory and Cognition has reached its conclusion. The association between effective language learning and good short-term memory is, it seems, not a causal relationship. It is not that a good short-term memory is a prerequisite for long-term learning; it is that both short-term and long-term memory tasks tap the same ability to create representations of sufficient quality to support the maintenance of several of them at once.
Another finding is that metaphoric language often puts greater stress on working memory and so is harder to process than literal language.
Another study looked at differences between the abilities of musicians and persons who did not have music as an active hobby to remember series of notes presented in succession on a computer screen. The results show how expertise makes it possible to apparently bypass working memory limits, even when the memory items cannot be grouped into simple categories.

http://www.eurekalert.org/pub_releases/2006-03/uoh-nrd031306.php
http://www.sciencedaily.com/releases/2006/03/060320084440.htm

Discovery disproves simple concept of memory as 'storage space'

The idea of memory “capacity” has become more and more eroded over the years, and now a new technique for measuring brainwaves seems to finally knock the idea on the head. Consistent with recent research suggesting that a crucial problem with aging is a growing inability to ignore distracting information, this new study shows that visual working memory depends on your ability to filter out irrelevant information. Individuals have long been characterized as having a “high” working memory capacity or a “low” one — the assumption has been that these people differ in their storage capacity. Now it seems it’s all about a neural mechanism that controls what information gets into awareness. People with high capacity have a much better ability to ignore irrelevant information.

[1091] Vogel, E. K., McCollough A. W., & Machizawa M. G.
(2005).  Neural measures reveal individual differences in controlling access to working memory.
Nature. 438(7067), 500 - 503.

http://www.eurekalert.org/pub_releases/2005-11/uoo-dds111805.php

How much can your mind keep track of?

A recent study has tried a new take on measuring how much a person can keep track of. It's difficult to measure the limits of processing capacity because most people automatically break down large complex problems into small, manageable chunks. To keep people from doing this, therefore, researchers created problems the test subjects wouldn’t be familiar with. 30 academics were presented with incomplete verbal descriptions of statistical interactions between fictitious variables, with an accompanying set of graphs that represented the interactions. It was found that, as the problems got more complex, participants performed less well and were less confident. They were significantly less able to accurately solve the problems involving four-way interactions than the ones involving three-way interactions, and were completely incapable of solving problems with five-way interactions. The researchers concluded that we cannot process more than four variables at a time (and at that, four is a strain).

[415] Halford, G. S., Baker R., McCredden J. E., & Bain J. D.
(2005).  How many variables can humans process?.
Psychological Science: A Journal of the American Psychological Society / APS. 16(1), 70 - 76.

http://www.eurekalert.org/pub_releases/2005-03/aps-hmc030805.php

Cognitive therapy for ADHD

A researcher that has previously demonstrated that working memory capacity can be increased through training, has now reported that the training software has produced significant improvement in children with ADHD — a disability that is associated with deficits in working memory. The study involved 53 children with ADHD, aged 7-12, who were not on medication for their disability. 44 of these met the criterion of more than 20 days of training. Half the participants were assigned to the working memory training program and the other half to a comparison program. 60% of those who underwent the wm training program no longer met the clinical criteria for ADHD after five weeks of training. The children were tested on visual-spatial memory, which has the strongest link to inattention and ADHD. Further research is needed to show that training improves ability on a wider range of tasks.

[583] Klingberg, T., Fernell E., Olesen P. J., Johnson M., Gustafsson P., Dahlström K., et al.
(2005).  Computerized Training of Working Memory in Children With ADHD-A Randomized, Controlled Trial.
Journal of the American Academy of Child & Adolescent Psychiatry. 44(2), 177 - 186.

http://www.sciam.com/article.cfm?articleID=000560D5-7252-12B9-9A2C83414B7F0000&sc=I100322

Anxiety adversely affects those who are most likely to succeed at exams

It has been thought that pressure harms performance on cognitive skills such as mathematical problem-solving by reducing the working memory capacity available for skill execution. However, a new study of 93 students has found that this applies only to those high in working memory. It appears that the advantage of a high working memory capacity disappears when that attention capacity is compromised by anxiety.

[355] Beilock, S. L., & Carr T. H.
(2005).  When high-powered people fail: working memory and "choking under pressure" in math.
Psychological Science: A Journal of the American Psychological Society / APS. 16(2), 101 - 105.

http://www.eurekalert.org/pub_releases/2005-02/bpl-wup020705.php

Development of working memory with age

An imaging study of 20 healthy 8- to 30-year-olds has shed new light on the development of working memory. The study found that pre-adolescent children relied most heavily on the prefrontal and parietal regions of the brain during the working memory task; adolescents used those regions plus the anterior cingulate; and in adults, a third area of the brain, the medial temporal lobe, was brought in to support the functions of the other areas. Adults performed best. The results support the view that a person's ability to have voluntary control over behavior improves with age because with development, additional brain processes are used.

http://www.eurekalert.org/pub_releases/2004-10/uopm-dow102104.php

Training improves working memory capacity

Working memory capacity has traditionally been thought to be constant. Recent studies, however, suggest that working memory can be improved by training. In this recent imaging study, it was found that adults who practiced working memory tasks for 5 weeks showed increased brain activity in the middle frontal gyrus and superior and inferior parietal cortices. These changes could be evidence of training-induced plasticity in the neural systems that underlie working memory.

Olesen, P.J., Westerberg, H. & Klingberg, T. 2004. Increased prefrontal and parietal activity after training of working memory. Nature Neuroscience, 7(1), 75-9.

http://www.nature.com/cgi-taf/DynaPage.taf?file=/neuro/journal/v7/n1/abs/nn1165.html

Tests for working memory capacity more limited than thought

The so-called “magic number 7” has been a useful mnemonic for working memory capacity — how many items you can hold in your working memory at one time — but we’ve known for some time that it isn’t quite as it was originally thought. Apart from the fact that the “7” is an average, and that the idea of an “item” is awfully vague as far as informational content is concerned, we have known for some time that what is really important is how long it takes for you to say the words. Thus, Chinese can hold on average 9 items, because the words used in the test are short and simple to pronounce, whereas the Welsh can hold only 5 on average, because of the length and complexity of their words. (note: it’s not because we actually say these words out loud). Similarly, the finding that deaf users of American Sign Language have an average of only 5 items was thought to be because signs take longer to utter. However, new research casts doubt on this theory. The researchers were trying to devise a sign-language test that would be comparable to a hearing language test. To their surprise they found that even when signs were faster to pronounce than spoken language, signers recalled only five items. Also, hearing individuals who were fluent in American Sign Language scored differently when asked to recall spoken lists in order, versus when they recalled signed lists (seven heard items remembered, five signed items remembered). Up until this time, the predominant idea was that the number found by this test was a good measure of overall cognitive capacity, but this assumption must now be in doubt. It's suggested that a test requiring recall of items, but not in temporal order, is a better measure of cognitive capacity. The results have important implications for standardized tests, which often employ ordered-list retention as a measure of a person's mental aptitude.

[422] Boutla, M., Supalla T., Newport E. L., & Bavelier D.
(2004).  Short-term memory span: insights from sign language.
Nat Neurosci. 7(9), 997 - 1002.

http://www.eurekalert.org/pub_releases/2004-08/uor-stm083104.php

Hippocampus and subiculum both critical for short-term memory

A new animal study has revealed that the hippocampus shares its involvement in short-term memory with an adjacent brain region, the subiculum. Both regions act together to establish and retrieve short-term memories. The process involves each region acting at different times, with the other region shutting off while the other is active. The shortest memories (10-15s) were found to be controlled almost exclusively by the subiculum. After 15s, the hippocampus took over. It was also found that the hippocampus appeared to respond in a way influenced by previous experiences, allowing it to anticipate future events on the basis of past outcomes. This is an advantage but can also cause errors.

[349] Deadwyler, S. A., & Hampson R. E.
(2004).  Differential but Complementary Mnemonic Functions of the Hippocampus and Subiculum.
Neuron. 42(3), 465 - 476.

http://www.eurekalert.org/pub_releases/2004-05/wfub-nrs050604.php

Why working memory capacity is so limited

There’s an old parlor game whereby someone brings into a room a tray covered with a number of different small objects, which they show to the people in the room for one minute, before whisking it away again. The participants are then required to write down as many objects as they can remember. For those who perform badly at this type of thing, some consolation from researchers: it’s not (entirely) your fault. We do actually have a very limited storage capacity for visual short-term memory.
Now visual short-term memory is of course vital for a number of functions, and reflecting this, there is an extensive network of brain structures supporting this type of memory. However, a new imaging study suggests that the limited storage capacity is due mainly to just one of these regions: the posterior parietal cortex. An interesting distinction can be made here between registering information and actually “holding it in mind”. Activity in the posterior parietal cortex strongly correlated with the number of objects the subjects were able to remember, but only if the participants were asked to remember. In contrast, regions of the visual cortex in the occipital lobe responded differently to the number of objects even when participants were not asked to remember what they had seen.

[598] Todd, J. J., & Marois R.
(2004).  Capacity limit of visual short-term memory in human posterior parietal cortex.
Nature. 428(6984), 751 - 754.

http://www.eurekalert.org/pub_releases/2004-04/vu-slo040704.php
http://tinyurl.com/2jzwe (Telegraph article)

Brain signal predicts working memory capacity

Our visual short-term memory may have an extremely limited capacity, but some people do have a greater capacity than others. A new study reveals that an individual's capacity for such visual working memory can be predicted by his or her brainwaves. In the study, participants briefly viewed a picture containing colored squares, followed by a one-second delay, and then a test picture. They pressed buttons to indicate whether the test picture was identical to -- or differed by one color -- from the one seen earlier. The more squares a subject could correctly identify having just seen, the greater his/her visual working memory capacity, and the higher the spike of corresponding brain activity – up to a point. Neural activity of subjects with poorer working memory scores leveled off early, showing little or no increase when the number of squares to remember increased from 2 to 4, while those with high capacity showed large increases. Subjects averaged 2.8 squares.

[1154] Vogel, E. K., & Machizawa M. G.
(2004).  Neural activity predicts individual differences in visual working memory capacity.
Nature. 428(6984), 748 - 751.

http://www.eurekalert.org/pub_releases/2004-04/niom-bsp041604.php

Small world networks key to working memory

A computer model may reveal an important aspect of working memory. The key, researchers say, is that the neurons form a "small world" network. In such a network, regardless of its size, any two points within them are always linked by only a small number of steps. Working memory may rely on the same property.

[2547] Micheloyannis, S., Pachou E., Stam C. J., Vourkas M., Erimaki S., & Tsirka V.
(2006).  Using graph theoretical analysis of multi channel EEG to evaluate the neural efficiency hypothesis.
Neuroscience Letters. 402(3), 273 - 277.

http://www.newscientist.com/article/mg18224481.600-its-a-small-world-inside-your-head.html

Memory-enhancing drugs for elderly may impair working memory and other executive functions

Drugs that increase the activity of an enzyme called protein kinase A improve long-term memory in aged mice and have been proposed as memory-enhancing drugs for elderly humans. However, the type of memory improved by this activity occurs principally in the hippocampus. A new study suggests that increased activity of this enzyme has a deleterious effect on working memory (which principally involves the prefrontal cortex). In other words, a drug that helps you remember a recent event may worsen your ability to remember what you’re about to do (to take an example).

Ramos, B.P., Birnbaum, S.G., Lindenmayer, I., Newton, S.S., Duman, R.S. & Arnsten, A.F.T. 2003. Dysregulation of Protein Kinase A Signaling in the Aged Prefrontal Cortex: New Strategy for Treating Age-Related Cognitive Decline. Neuron, 40, 835-845.

http://www.eurekalert.org/pub_releases/2003-11/naos-mdf110303.php

Sleep deprivation affects working memory

A recent study investigated the working memory capacities of individuals who were sleep-deprived. For nine days, 7 of the 12 participants slept four hours each night, and 5 slept for eight hours. Each morning, participants completed a computer task to measure how quickly they could access a list of numbers they had been asked to memorize. The list could be one, three, or five items long. Then participants were presented with a series of single digits and asked to answer "yes" or "no" to indicate whether each digit was one they had memorized. Those who slept eight hours a night steadily increased their working memory efficiency on this task, but those who slept only four hours a night failed to show any improvement in memory efficiency. Motor skill did not change across days for either group of participants.

Casement, M.D., Mullington, J.M., Broussard, J.L., & Press, D.Z. 2003. The effects of prolonged sleep restriction on working memory performance. Paper presented at the annual meeting of the Society for Neuroscience, New Orleans, LA.

http://www.eurekalert.org/pub_releases/2003-11/sfn-sfb_1111003.php

Gesturing reduces cognitive load

Why is it that people cannot keep their hands still when they talk? One reason may be that gesturing actually lightens cognitive load while a person is thinking of what to say. Adults and children were asked to remember a list of letters or words while explaining how they solved a math problem. Both groups remembered significantly more items when they gestured during their math explanations than when they did not gesture.

[1300] Goldin-Meadow, S., Nusbaum H., Kelly S. D., & Wagner S.
(2001).  Explaining math: gesturing lightens the load.
Psychological Science: A Journal of the American Psychological Society / APS. 12(6), 516 - 522.

Stereotype threat

Older news items (pre-2010) brought over from the old website

Positive stereotypes can offset negative stereotype effect

A number of studies have now shown that negative stereotypes can impair cognitive performance, mainly through adding to working memory load. A new study has now shown that this effect can be mitigated by the activation of a positive stereotype. The research takes advantage of the fact that we all belong to several social groups. In this case, the relevant groups were ‘female’ and ‘college student’. As usual, when (subtly) reminded of negative stereotypes for women and math, women performed worse. The interesting thing was that this didn’t happen if women were also made aware that college students performed better at math than non-college students. Moreover, this was reflected in working memory capacity. It seems that, when both a positive and a negative stereotype are offered, people will tend to choose the positive stereotype, and the effects of this will cancel out the negative stereotype. It’s also worth noting how easily these stereotypes are activated: effects could be manipulated simply by subtly changing demographic questions asked before the test (and it is not uncommon that test-takers are first required to answer some demographic questions).

[1381] Rydell, R. J., McConnell A. R., & Beilock S. L.
(2009).  Multiple social identities and stereotype threat: Imbalance, accessibility, and working memory..
Journal of Personality and Social Psychology. 96(5), 949 - 966.

http://www.eurekalert.org/pub_releases/2009-05/iu-pob050109.php

Implicit stereotypes and gender identification may affect female math performance

Another study has come out showing that women enrolled in an introductory calculus course who possessed strong implicit gender stereotypes, (for example, automatically associating "male" more than "female" with math ability and math professions) and were likely to identify themselves as feminine, performed worse relative to their female counterparts who did not possess such stereotypes and who were less likely to identify with traditionally female characteristics. Strikingly, a majority of the women participating in the study explicitly expressed disagreement with the idea that men have superior math ability, suggesting that even when consciously disavowing stereotypes, female math students are still susceptible to negative perceptions of their ability.

[969] Kiefer, A. K., & Sekaquaptewa D.
(2007).  Implicit stereotypes, gender identification, and math-related outcomes: a prospective study of female college students.
Psychological Science: A Journal of the American Psychological Society / APS. 18(1), 13 - 18.

http://www.eurekalert.org/pub_releases/2007-01/afps-isa012407.php

Reducing the racial achievement gap

And staying with the same theme, a study that came out six months ago, and recently reviewed on the excellent new Scientific American Mind Matters blog, revealed that a single, 15-minute intervention erased almost half the racial achievement gap between African American and white students. The intervention involved writing a brief paragraph about which value, from a list of values, was most important to them and why. The intervention improved subsequent academic performance for some 70% of the African American students, but none of the Caucasians. The study was repeated the following year with the same results. It is thought that the effect of the intervention was to protect against the negative stereotypes regarding the intelligence and academic capabilities of African Americans.

[1082] Cohen, G. L., Garcia J., Apfel N., & Master A.
(2006).  Reducing the Racial Achievement Gap: A Social-Psychological Intervention.
Science. 313(5791), 1307 - 1310.

Women's math performance affected by theories on sex differences

In a salutary reminder to all researchers into gender and race differences, researchers found that women who received a genetic explanation for female underachievement in math or were reminded of the stereotype about female math underachievement, performed more poorly on math tests than those who received an experiential explanation (such as math teachers treating boys preferentially during the first years of math education) or were led to believe there are no sex differences in math.

[1024] Dar-Nimrod, I., & Heine S. J.
(2006).  Exposure to Scientific Theories Affects Women's Math Performance.
Science. 314(5798), 435 - 435.

http://www.eurekalert.org/pub_releases/2006-10/uobc-wmp101306.php

Interactions with other races can impair mental capacity in the strongly prejudiced

A new approach on an old theme — the effect of stress on cognitive function. The study looked at the short-term effects of racial prejudice. White college students were assessed for racial bias and then had a conversation with either a black or white person. After the conversation, they were given the Stroop test (participants are presented with color words, which are either in the same color as they name, or not; they are required to respond on the basis of the color of the word, not the name. The test requires a surprising amount of concentration.) For those who had talked with a black person, the greater the amount of racial bias, the worse the student did on the Stroop test. This is assumed to be due to the stress caused by the interaction.

[833] Richeson, J. A., & Shelton N. J.
(2003).  When prejudice does not pay: Effects of Interracial Contact on Executive Function.
Psychological Science. 14(3), 287 - 290.

http://www.eurekalert.org/pub_releases/2003-04/pu-tpo043003.php

Fear & Trauma

See also PTSD

Older news items (pre-2010) brought over from the old website

Scent of fear impacts cognitive performance

A study involving 75 female students found that those who were exposed to chemicals from fear-induced sweat performed more accurately on word-association tasks than did women exposed to chemicals from other types of sweat or no sweat at all. When processing meaningfully related word pairs, the participants exposed to the fear chemicals were significantly more accurate than those in either the neutral sweat or the control (no-sweat) condition. When processing word pairs that were ambiguous in threat content, such as one neutral word paired with a threatening word or a pair of neutral words, subjects in the fear condition were significantly slower in responding than those in the neutral sweat condition.

Chen, D., Katdare, A. & Lucas, N. 2006. Chemosignals of Fear Enhance Cognitive Performance in Humans. Chemical Senses, Advance Access published on March 9, 2006

http://www.eurekalert.org/pub_releases/2006-03/ru-sof033106.php

Memory of fear more complex than supposed

It seems that fear memory is more complex than has been thought. A new mouse study has shown that not only the hippocampus and amygdala are involved, but that the prefrontal cortex is also critical. The development of the fear association doesn’t occur immediately after a distressing event, but develops over time. The process, it now seems, depends directly on a protein called NR2B.

[243] Li, B-M., Zhao M-G., Toyoda H., Lee Y-S., Wu L-J., Ko S. W., et al.
(2005).  Roles of NMDA NR2B Subtype Receptor in Prefrontal Long-Term Potentiation and Contextual Fear Memory.
Neuron. 47(6), 859 - 872.

http://www.eurekalert.org/pub_releases/2005-09/uot-sco091505.php

How trauma triggers long-lasting memories in the brain

A rat study sheds more light on why emotional experiences tend to be better remembered than emotionally neutral events. The study found that emotionally arousing events activated the amygdala, which then increased a specific protein — activity-regulated cytoskeletal protein ("Arc") — in the neurons in the hippocampus. It's thought that Arc helps store these memories by strengthening the synapses.

[922] McIntyre, C. K., Miyashita T., Setlow B., Marjon K. D., Steward O., Guzowski J. F., et al.
(2005).  Memory-influencing intra-basolateral amygdala drug infusions modulate expression of Arc protein in the hippocampus.
Proceedings of the National Academy of Sciences of the United States of America. 102(30), 10718 - 10723.

http://www.eurekalert.org/pub_releases/2005-07/uoc--nih072505.php

Why traumatic memories have the power they do

In the first imaging study to look at retrieval of emotional memories after a long period (one year after encoding), researchers found that people did recall emotional images, both pleasant and unpleasant, better than emotionally-neutral images. This recall was associated with higher activity in both the amygdala and the hippocampus. The synchronicity of activity between these two regions suggested that each region triggers the other, creating a self-reinforcing "memory loop" in which an emotional cue might trigger recall of the event, which then loops back to a re-experiencing of the emotion of the event. The findings suggest why people subject to traumatic events may be trapped in a cycle of emotion and recall that aggravates post-traumatic stress disorder, and may also suggest why therapies in which people relive such memories and reshape perspective to make it less traumatic can help people cope with such memories.

[198] Dolcos, F., LaBar K. S., & Cabeza R.
(2005).  Remembering one year later: Role of the amygdala and the medial temporal lobe memory system in retrieving emotional memories.
Proceedings of the National Academy of Sciences of the United States of America. 102(7), 2626 - 2631.

http://www.eurekalert.org/pub_releases/2005-03/du-ems030805.php

Reducing the trauma of traumatic memories

For some, stressful memories can reawaken intense fear, with undesirable consequences. A new study involving mice has found that such stress induces a change in the expression of the acetylcholinesterase gene, which normally produces a vital protein that adheres to neuronal synapses. Following stress, however, the same gene produces large quantities of a protein with modified properties that results in heightened electrical signals in the nerve cells communicating through these synapses. The effect is to create reactions of extreme fright or immobilizing shock. Later encounter with a context which triggers those stressful memories can set off that same neuronal reaction. The researchers have developed an "antisense" agent that acts to neutralize the process whereby the modified protein is produced, thereby preventing the extreme reaction.

[1002] Soreq, H., Blank T., Nijholt I., Farchi N., Kye M., Sklan E. H., et al.
(2003).  Stress-induced alternative splicing of acetylcholinesterase results in enhanced fear memory and long-term potentiation.
Mol Psychiatry. 9(2), 174 - 183.

http://www.eurekalert.org/pub_releases/2003-12/huoj-hug121103.php
http://www.eurekalert.org/pub_releases/2003-12/mp-abm120803.php

Stress & anxiety

Older news items (pre-2010) brought over from the old website

Short stressful events may improve working memory

We know that chronic stress has a detrimental effect on learning and memory, but a new rat study shows how acute stress (a short, sharp event) can produce a beneficial effect. The rats, trained to a level of 60-70% accuracy on a maze, were put through a 20-minute forced swim before being run through the maze again. Those who experienced this stressful event were better at running the maze 4 hours later, and a day later, than those not forced through the stressful event. It appears that the stress hormone corticosterone (cortisol in humans) increases transmission of the neurotransmitter glutamate in the prefrontal cortex and improves working memory. It also appears that chronic stress suppresses the transmission of glutamate in the prefrontal cortex of male rodents, while estrogen receptors in female rodents make them more resilient to chronic stress than male rats.

[1157] Yuen, E. Y., Liu W., Karatsoreos I. N., Feng J., McEwen B. S., & Yan Z.
(2009).  Acute stress enhances glutamatergic transmission in prefrontal cortex and facilitates working memory.
Proceedings of the National Academy of Sciences of the United States of America. 106(33), 14075 - 14079.

http://www.eurekalert.org/pub_releases/2009-07/uab-sse072309.php

Stressed brains rely on habit

And another rat study has found that rats stressed repeatedly and unpredictably for three weeks were more likely than unstressed animals to continue performing habitual behaviors, even when it no longer made sense to do so. This behavior was correlated with reductions in the prelimbic cortex of the medial prefrontal cortex and the dorsomedial striatum (both implicated in goal-directed actions), and increases in the size of the dorsolateral striatum (necessary for habit). The finding follows on from previous research showing that habit formation involves a switch between neural circuits associated with goal-directed behavior and those controlling habitual behavior. The findings have implications for therapies for stress-related disorders and addictive behavior.

[517] Dias-Ferreira, E., Sousa J. C., Melo I., Morgado P., Mesquita A. R., Cerqueira J. J., et al.
(2009).  Chronic Stress Causes Frontostriatal Reorganization and Affects Decision-Making.
Science. 325(5940), 621 - 625.

http://www.the-scientist.com/blog/display/55873/

Stress disrupts task-switching, but the brain can bounce back

A new neuroimaging study involving 20 male M.D. candidates in the middle of preparing for their board exams has found that they had a harder time shifting their attention from one task to another after a month of stress than other healthy young men who were not under stress. The finding replicates what has been found in rat studies, and similarly correlates with impaired function in an area of the prefrontal cortex that is involved in attention. However, the brains recovered their function within a month of the end of the stressful period.

[829] Liston, C., McEwen B. S., & Casey B. J.
(2009).  Psychosocial stress reversibly disrupts prefrontal processing and attentional control.
Proceedings of the National Academy of Sciences. 106(3), 912 - 917.

Full text available at http://www.pnas.org/content/106/3/912.abstract
http://www.eurekalert.org/pub_releases/2009-01/ru-sdh012709.php

Psychological distress, not depression, linked to increased risk of stroke

A study following 20,627 people for an average of 8.5 years has found that psychological distress was associated with an increased risk of stroke and that the risk of stroke increased the more distress the participants reported. This association remained the same regardless of cigarette smoking, systolic blood pressure, overall blood cholesterol, obesity, previous heart attack, diabetes, social class, education, high blood pressure treatment, family history of stroke and recent antidepressant medication use. However, there was no increased risk for people who had experienced an episode of major depression in the past year or at any point in their lifetime.

[1298] Surtees, P. G., Wainwright N. W. J., Luben R. N., Wareham N. J., Bingham S. A., & Khaw K. - T.
(2008).  Psychological distress, major depressive disorder, and risk of stroke.
Neurology. 70(10), 788 - 794.

http://www.eurekalert.org/pub_releases/2008-03/aaon-pdn022608.php

Short-term stress can affect learning and memory

We know that long-lasting, severe stress can impair cell communication in the hippocampus. Now rodent studies have demonstrated that the same outcome can happen with short-term stress. But rather than involving the familiar stress hormone cortisol, acute stress activated corticotropin releasing hormones, which led to the rapid disintegration of dendritic spines in the hippocampus, thus limiting the ability of synapses to collect and store memories.

[981] Chen, Y., Dube C. M., Rice C. J., & Baram T. Z.
(2008).  Rapid Loss of Dendritic Spines after Stress Involves Derangement of Spine Dynamics by Corticotropin-Releasing Hormone.
J. Neurosci.. 28(11), 2903 - 2911.

http://www.eurekalert.org/pub_releases/2008-03/uoc--ssc031008.php

Correct levels of stress hormones boost learning

Although it’s known that cortisol production is related to stress and has an impact on learning in humans, that impact is not well understood, because of the difficulties of controlling cortisol levels in humans. A study using ground squirrels has now found that they learn more quickly if they have a modest amount of cortisol, rather than either high or low levels of cortisol.

[252] Mateo, J. M.
(2008).  Inverted-U shape relationship between cortisol and learning in ground squirrels.
Neurobiology of Learning and Memory. 89(4), 582 - 590.

http://www.eurekalert.org/pub_releases/2008-03/uoc-rws031208.php

Stress hormone impacts memory, learning in diabetic rodents

A rodent study sheds light on why diabetes can impair cognitive function. The study found that increased levels of a stress hormone (called cortisol in humans) in diabetic rats impaired synaptic plasticity and reduced neurogenesis in the hippocampus. When levels returned to normal, the hippocampus recovered. Cortisol production is controlled by the hypothalamic-pituitary axis (HPA). People with poorly controlled diabetes often have an overactive HPA axis and excessive cortisol.

[1050] Stranahan, A. M., Arumugam T. V., Cutler R. G., Lee K., Egan J. M., & Mattson M. P.
(2008).  Diabetes impairs hippocampal function through glucocorticoid-mediated effects on new and mature neurons.
Nature Neuroscience. 11(3), 309 - 317.

http://www.eurekalert.org/pub_releases/2008-02/nioa-shi021508.php

How stress affects memory

We know stress affects memory. Now a rat study tells us one of the ways it does that. Cell recordings in the hippocampus revealed that, when a mouse moves from one location to another, particular cells fired at each location. When the mouse returned to an earlier location, the same cells fire. However, following stress, the cells that fired in a particular location still fired at the same location, but tended to fire at a different frequency. Stress also reduce the level of LTP at the synapses.

[1295] Kim, J. J., Lee H. J., Welday A. C., Song EY., Cho J., Sharp P. E., et al.
(2007).  Stress-induced alterations in hippocampal plasticity, place cells, and spatial memory.
Proceedings of the National Academy of Sciences. 104(46), 18297 - 18302.

http://www.sciencentral.com/articles/view.php3?article_id=218393035

Highly accomplished people more prone to failure than others when under stress

One important difference between those who do well academically and those who don’t is often working memory capacity. Those with a high working memory capacity find it easier to read and understand and reason, than those with a smaller capacity. However, a new study suggests there is a downside. Such people tend to heavily rely on their abundant supply of working memory and are therefore disadvantaged when challenged to solve difficult problems, such as mathematical ones, under pressure — because the distraction caused by stress consumes their working memory. They then fall back on the less accurate short-cuts that people with less adequate supplies of working memory tend to use, such as guessing and estimation. Such methods are not made any worse by working under pressure. In the study involving 100 undergraduates, performance of students with strong working memory declined to the same level as those with more limited working memory, when the students were put under pressure. Those with more limited working memory performed as well under added pressure as they did without the stress.

The findings were presented February 17 at the annual meeting of the American Association for the Advancement of Science.

http://www.eurekalert.org/pub_releases/2007-02/uoc-hap021607.php

Lifestyle changes improve seniors’ memory surprisingly quickly

A small 14-day study found that those following a memory improvement plan that included memory training, a healthy diet, physical exercise, and stress reduction, showed a 5% decrease in brain metabolism in the dorsal lateral prefrontal region of the brain (involved in working memory) suggesting they were using their brain more efficiently. This change in activity was reflected in better performance on a cognitive measure controlled by this brain region, and participants reported that they felt their memory had improved. The memory training involved doing brainteasers, crossword puzzles and memory exercises. Diet involved eating 5 small meals daily (to prevent fluctuations in blood glucose levels) that were rich in omega-3 fats, low-glycemic index carbohydrates (e.g., whole grains) and antioxidants. Physical exercise involved brisk walking and stretching, and stress reduction involved stretching and relaxation exercises.

The study was presented at the American College of Neuropsychopharmacology's Annual Meeting on December 11-15, in Hawaii.

http://www.eurekalert.org/pub_releases/2005-12/g-nsf121205.php

Stress interferes with problem-solving; Beta-blocker may help

New research suggests that an experience as simple as watching graphically violent or emotional scenes in a movie can induce enough stress to interfere with problem-solving abilities, and that a beta-blocker medication could promote the ability to think flexibly under stressful conditions. Neither the stress nor the beta-blocker affected memory. The research not only has implications for understanding the range of effects of stress on thinking, but could also have broader clinical implications for patients with anxiety disorders or substance abuse problems.

Renner, K., Alexander, J., Hillier, A., Smith, R. & Tivarus, M. 2005. Presented at the annual Society for Neuroscience meeting in Washington, D.C.

http://www.eurekalert.org/pub_releases/2005-11/osu-siw110905.php

Early life stress can lead to memory loss and cognitive decline in middle age

Age-related cognitive decline is probably a result of both genetic and environmental factors. A rat study has demonstrated that some of these environmental factors may occur in early life. Among the rats, emotional stress in infancy showed no ill effects by the time the rats reached adulthood, but as the rats reached middle age, cognitive deficits started to appear in those rats who had had stressful infancies, and progressed much more rapidly with age than among those who had had nurturing infancies. Middle-aged rats who had been exposed to early life emotional stress showed deterioration in brain-cell communication in the hippocampus.

[1274] Brunson, K. L., Kramar E., Lin B., Chen Y., Colgin L L., Yanagihara T. K., et al.
(2005).  Mechanisms of Late-Onset Cognitive Decline after Early-Life Stress.
J. Neurosci.. 25(41), 9328 - 9338.

http://www.eurekalert.org/pub_releases/2005-10/uoc--els100605.php

Stress bad for the brain

A study of older adults for three to six years has found that those with continuous high levels of the stress hormone cortisol performed poorly on memory tests and had a 14% smaller hippocampus. A further study involving young adults and children between the ages of six and fourteen found that even an acute increase in cortisol can lead to reversible memory impairments in young adults, and that children from low socio-economic status environments had higher cortisol levels than those from high SES homes. Children from low SES homes tended to process positive and negative attributes more negatively than children from high SES homes, and this type of processing was significantly related to basal cortisol levels at ages 10, 12 and 14.

[1415] Lupien, S. J., Fiocco A. J., Wan N., Maheu F., Lord C., Schramek T., et al.
(2005).  Stress hormones and human memory function across the lifespan.
Psychoneuroendocrinology. 30(3), 225 - 242.

http://www.eurekalert.org/pub_releases/2005-05/mu-tst051705.php

Anxiety adversely affects those who are most likely to succeed at exams

It has been thought that pressure harms performance on cognitive skills such as mathematical problem-solving by reducing the working memory capacity available for skill execution. However, a new study of 93 students has found that this applies only to those high in working memory. It appears that the advantage of a high working memory capacity disappears when that attention capacity is compromised by anxiety.

[355] Beilock, S. L., & Carr T. H.
(2005).  When high-powered people fail: working memory and "choking under pressure" in math.
Psychological Science: A Journal of the American Psychological Society / APS. 16(2), 101 - 105.

http://www.eurekalert.org/pub_releases/2005-02/bpl-wup020705.php

Anxiety good for memory recall, bad for solving complex problems

Cognitive tests given to 19 first-year medical students one to two days before a regular classroom exam, and then a week after the exam, found that, before the exam, students were better able to accurately recall a list of memorized numbers, but did less well on tests that required them to consider many possibilities in order to come up with a reasonable answer. A week after the exam, the opposite was true. It is assumed that the difference in results reflects the effects of stress.

Jessa Alexander & David Beversdorf presented their findings on October 25 in San Diego at the annual Society for Neuroscience conference.

http://www.eurekalert.org/pub_releases/2004-10/osu-agf101904.php

Estrogen effect on memory influenced by stress

The question of whether estrogen helps memory and cognition in women has proven surprisingly difficult to answer, with studies giving conflicting results. Now it seems the answer to that confusion is: it depends. And one of the things it depends on may be the level of stress the woman is experiencing. A rat study has found that the performance of female rats in a water maze was affected by the interaction of hormone level (whether the rat was estrous or proestrous) with water temperature (a source of physical stress). Those rats with high hormone levels did better when the water was warm, while those with low hormone levels did better when the water was cold. The researchers suggest both timing and duration of stress might be factors in determining the effect of hormones on cognition.

[384] Rubinow, M. J., Arseneau L. M., Beverly L. J., & Juraska J. M.
(2004).  Effect of the Estrous Cycle on Water Maze Acquisition Depends on the Temperature of the Water..
Behavioral Neuroscience. 118(4), 863 - 868.

http://www.eurekalert.org/pub_releases/2004-08/uoia-sss082704.php

Stress reactions no guarantee of authenticity

Physical stress reactions have often been taken as evidence for the authenticity of a memory. A recent study investigated people with “memories” of alien abductions (on the grounds that these are the memories least likely to be true) and found that those who believed they had been abducted by aliens responded physically to recall of that memory in the same way as to recall of other, true, stressful events. The finding suggests that a person’s reaction to a memory is no evidence for whether or not it truly happened.

[1161] McNally, R. J., Lasko N. B., Clancy S. A., Macklin M. L., Pitman R. K., & Orr S. P.
(2004).  Psychophysiological responding during script-driven imagery in people reporting abduction by space aliens.
Psychological Science: A Journal of the American Psychological Society / APS. 15(7), 493 - 497.

http://www.eurekalert.org/pub_releases/2004-06/aps-ptw062104.php

Stress no aid to memory

Numerous studies have questioned the accuracy of recall of traumatic events, but the research is often dismissed as artificial and not intense enough to simulate real-life trauma. A new study has used real stress: 509 active duty military personnel enrolled in survival school training were deprived of food and sleep 48 hours and then interrogated. A day later, only 30% of those presented with a line-up could identify the right person, only 34% identified their interrogator from a photo-spread and 49% from single photos shown sequentially (putting the interrogator in the same clothing boosted correct identification to 66%). Thirty people even got the gender wrong. Those subjected to physical threats (half the participants) performed worse.

[269] Morgan, C. A., Hazlett G., Doran A., Garrett S., Hoyt G., Thomas P., et al.
(Submitted).  Accuracy of eyewitness memory for persons encountered during exposure to highly intense stress.
International Journal of Law and Psychiatry. 27(3), 265 - 279.

http://www.newscientist.com/news/news.jsp?id=ns99995089
http://www.eurekalert.org/pub_releases/2004-06/yu-emp060304.php
http://www.eurekalert.org/pub_releases/2004-06/ns-mfy060904.php

Anxiety over math blocks learning

The so-called "math block" is notorious - why do we have such a term? Do we talk about a "geography block", or a "physics block"? But we do talk of a reading block. Perhaps the reason for both is the same.
The amount of information you can work with at one time has clear limits, defined by your working memory capacity. When we are anxious, part of our working memory is taken up with our awareness of these fears and worries, leaving less capacity available for processing (which is why students who are very anxious during exams usually perform well below their capabilities). Processes such as reading and working with numbers are very sensitive to working memory capacity because they place such demands on it.
A recently reported study by Mark H. Ashcraft and Elizabeth P. Kirk, both psychologists at Cleveland (Ohio) State University, provides the first solid evidence that, indeed, math-anxious people have working memory problems as they do math.

[2549] Ashcraft, M. H., & Kirk E. P.
(2001).  The relationships among working memory, math anxiety, and performance.
Journal of Experimental Psychology: General. 130(2), 224 - 237.

http://www.sciencenews.org/20010630/fob4.asp

tags memworks: 

Individual differences

Older news items (pre-2010) brought over from the old website

Learning styles challenged

A review of the research on learning styles finds that although numerous studies have claimed to show the existence of different kinds of learners, nearly all of the studies fail to satisfy key criteria for scientific validity — in particular, by randomly assigning learners classified by their “style” to one of several different learning methods (implicit in the idea of learning styles is the concept that individuals differ in regard to what mode of instruction or study is most effective for them). Of the few that did, some provided evidence flatly contradictory to the meshing hypothesis (the most common hypothesis, postulating that instruction is best provided in a format that matches the preferences of the learner) and the few findings in line with the idea did not assess popular learning-style schemes (71 different models of learning styles have been proposed over the years). The reviewers do no contest that people have preferences in how information is presented to them, or that people differ in the degree to which they use different processing modes, or that there might be untested learning styles that have significant effects. However, they argue that the lack of evidence for the postulated interaction effect is good reason not to spend limited education resources on this area that would better be devoted to adopting other educational practices that have a strong evidence base.

Pashler, H., McDaniel, M., Rohrer, D., & Bjork, R. (2009). Learning Styles: Concepts and Evidence. Psychological Science in the Public Interest, 9(3), 105-119.

http://www.eurekalert.org/pub_releases/2009-12/afps-lsd121609.php

Insight into the processes of 'positive' and 'negative' learners

An intriguing study of the electrical signals emanating from the brain has revealed two types of learners. A brainwave event called an "event-related potential" (ERP) is important in learning; a particular type of ERP called "error-related negativity" (ERN), is associated with activity in the anterior cingulate cortex. This region is activated during demanding cognitive tasks, and ERNs are typically more negative after participants make incorrect responses compared to correct choices. Unexpectedly, studies of this ERN found a difference between "positive" learners, who perform better at choosing the correct response than avoiding the wrong one, and "negative" learners, who learn better to avoid incorrect responses. The negative learners showed larger ERNs, suggesting that "these individuals are more affected by, and therefore learn more from, their errors.” Positive learners had larger ERNs when faced with high-conflict win/win decisions among two good options than during lose/lose decisions among two bad options, whereas negative learners showed the opposite pattern.

Frank, M.J., Woroch, B.S. & Curran, T. 2005. Error-Related Negativity Predicts Reinforcement Learning and Conflict Biases. Neuron, 47, 495-501.

http://www.eurekalert.org/pub_releases/2005-08/cp-iit081205.php

tags memworks: 

Consolidation

Older news items (pre-2010) brought over from the old website

Reactivating single memory does not affect associated memories

Recent studies have indicated that consolidated memories can in fact be manipulated when reactivated. This process, often referred to as reconsolidation, has been proposed as a possible way of treating traumatic memories. But one concern is that reactivating and disrupting a single memory may also affect other associated memories. A new rat study has found that only those memories directly reactivated are vulnerable, not those associated to them.

Debiec, J., Doyère, V., Nader, K. & LeDoux, J.E. 2006. Directly reactivated, but not indirectly reactivated, memories undergo reconsolidation in the amygdala. Proceedings of the National Academy of Sciences, 103 (9), 3428-3433.

http://www.eurekalert.org/pub_releases/2006-02/nyu-nrs021306.php

Protein found to inhibit conversion to long-term memory

In a study using genetically engineered mice, researchers have found that mice without a protein called GCN2 acquire new information that doesn’t fade as easily as it does in normal mice. After weak training on the Morris water maze, their spatial memory was enhanced, but it was impaired after more intense training. The researchers concluded that GCN2 may prevent new information from being stored in long-term memory, suggesting the conversion of new information into long-term memory requires both the activation of molecules that facilitate memory storage, and the silencing of proteins such as GCN2 that inhibit memory storage.

Wingfield, A., Tun, P.A. & McCoy, S.L. 2005. Hearing Loss in Older Adulthood: What It Is and How It Interacts With Cognitive Performance. Current Directions in Psychological Science, 14(3), 144-148.

http://www.eurekalert.org/pub_releases/2005-08/uom-mrp082905.php

New theory challenges current view of how brain stores long-term memory

The current view of long-term memory storage is that, at the molecular level, new proteins are manufactured (a process known as translation), and these newly synthesized proteins subsequently stabilize the changes underlying the memory. Thus, every new memory results in a permanent representation in the brain. A new theory of memory storage suggests instead that there is no permanent representation. Rather, memories are copied across many different brain networks. The advantage is that it is a highly flexible system, enabling rapid retrieval even of infrequent elements.
The theory suggests that the brain stores long-term memory by rapidly changing the shape of proteins already present at those synapses activated by learning. The theory explains a number of phenomena that are not properly answered by the existing theory. The theory doesn’t disagree with the view that it is the synapse that is modified in response to learning; the disagreement concerns how that synaptic modification occurs. Current theory says it is brought about by recently synthesized proteins; the new theory suggests that learning leads to a post-synthesis (post-translational) synaptic protein modification that results in changes to the shape, activity and/or location of existing synaptic proteins. It is suggested that long-term memory storage relies on a positive-feedback rehearsal system that continually updates or fine-tunes post-translational modification of previously modified synaptic proteins, thus allowing for the continual modifications of memories.

Routtenberg, A. & Rekart, J.L. 2005. Post-translational protein modification as the substrate for long-lasting memory. Trends in Neurosciences, 28 (1), 12-19.

http://www.eurekalert.org/pub_releases/2005-01/nu-ntc011405.php
http://www.sciencedirect.com/science/journal/01662236

Brain circuit crucial for memory consolidation identified

A rat study has identified a circuit in the brain that appears crucial in converting short-term memories into long-term memories. The circuit is the temporoammonic (TA) projection, which directly links the CA1 region of the hippocampus and the neocortex.

Remondes, M. &Schuman, E.M. 2004. Role for a cortical input to hippocampal area CA1 in the consolidation of a long-term memory.Nature, 431, 699 - 703.

http://www.eurekalert.org/pub_releases/2004-10/hhmi-bcm100604.php

Confirmation that a memory code is held in many different regions

Mapping of brain activity patterns has cast new light on how our memories integrate sights, smells, tastes, and sounds. Previous research has shown that the visual and auditory brain regions are activated during memories of pictures and sounds. A new imaging study investigated taste and smell. Volunteers were presented with random combinations of an odor and the image of an object and asked to imagine a link or story that associated the two. They were then presented with a series of both previously seen images and new images and asked to recall whether they were viewing new or old images. It was found that the region involved in processing smells, the piriform cortex, was activated when participants saw objects previously associated with odors. On questioning, participants said they recalled the story linking image and smell, but had not tried to summon up the smell itself. These findings confirm models of memory recall in which the sensory-specific components of a memory are preserved in the sensory-related brain regions, and the hippocampus draws on those components to reconstruct a sensory-rich memory (as opposed to the complete memory being stored in one place). This allows memories to be recalled from one sensory cue.

Gottfried, J.A., Smith, A.P.R., Rugg, M.D. & Dolan, R.J. 2004. Remembrance of Odors Past: Human Olfactory Cortex in Cross-Modal Recognition Memory. Neuron, 42 (4), 687-695.

http://www.eurekalert.org/pub_releases/2004-05/cp-hoh052104.php
http://www.eurekalert.org/pub_releases/2004-05/ucl-ros052404.php

Memories are harder to forget than recently thought

Previous rodent studies have shown that the process of encoding a memory can be blocked by the use of a protein synthesis inhibitor called anisomycin ( http://www.eurekalert.org/pub_releases/2000-08/NYU-Nnfl-1508100.htm). Experiments with anisomycin helped lead to the acceptance of a theory in which a learned behavior is consolidated into a stored form and that then enters a 'labile' - or adaptable - state when it is recalled. According to these previous studies, the act of putting a labile memory back into storage involves a reconsolidation process identical to the one used to store the memory initially. Indeed, experiments showed that anisomycin could make a mouse forget a memory if it were given anisomycin directly after remembering an event. In a new study, however, researchers have showed that disruption of a "re-remembered" memory was not permanent. Mice demonstrated that they could remember the original learned behavior 21 days later. This research thus casts doubt on the concept of “reconsolidation”, or at least demonstrates that we still have much to learn about this process.

Lattal, K.M. & Abel, T. 2004. Behavioral impairments caused by injections of the protein synthesis inhibitor anisomycin after contextual retrieval reverse with time. PNAS, 101, 4667-4672

http://www.eurekalert.org/pub_releases/2004-03/uop-mah031504.php

Another step in understanding how memories are formed

The electrical activity of individual neurons in the brains of two adult rhesus monkeys was monitored while the monkeys played a memory-based video game in which an image pops up on the computer screen with four targets—white dots—superimposed on it. The monkeys’ task was to learn which target on which image was associated with a reward (a drop of their favorite fruit juice). Dramatic changes in the activity of some hippocampal neurons, which the scientists called "changing cells", paralleled their learning, indicating that these neurons are involved in the initial formation of new associative memories. In some of the cells, activity continued after the animal had learned the association, suggesting that these cells may participate in the eventual storage of the associations in long-term memory.

Wirth, S., Yanike, M., Frank, L.M., Smith, A.C., Brown, E.N. & Suzuki, W.A. 2003. Single Neurons in the Monkey Hippocampus and Learning of New Associations. Science, 300, 1578-1581.

http://www.eurekalert.org/pub_releases/2003-06/nyu-fir060503.php

More details about how memories are formed in the hippocampus

We know how important the hippocampus is in forming memories, but now, using newly developed imaging techniques, researchers have managed to observe how activity patterns within specific substructures of the hippocampus change during learning. The study identified areas within the hippocampus (the cornu ammonis and the dentate gyrus) as highly active during encoding of face-name pairs. This activity decreased as the associations were learned. A different area of the hippocampus (the subiculum) was active primarily during the retrieval of the face-name associations. Activity in the subiculum also decreased as retrieval became more practiced.

Zeineh, M.M., Engel, S.A., Thompson, P.M. & Bookheimer, S.Y. 2003. Dynamics of the Hippocampus During Encoding and Retrieval of Face-Name Pairs, Science, 299, 577-580.

http://www.eurekalert.org/pub_releases/2003-01/uoc--som012303.php

Memories may be hard to find when thalamus fails to synchronize rhythms

Memory codes - the representation of an object or experience in memory - are patterns of connected neurons. The neurons that are linked are not necessarily in the same region of the brain. Exciting new research has measured the electrical rhythms that parts of the brain use to communicate with each other and found that the thalamus regulates these rhythms. "Memory appears to be a constructive process in combining the features of the items to be remembered rather than simply remembering each object as a whole form. The thalamus seems to direct or modulate the brain's activity so that the regions needed for memory are connected." The authors suggest that tips of the tongue experiences (when only part of a memory is recalled) may occur when the rhythms don't synchronize with the regions properly.

Slotnick, S.D., Moo, L.R., Kraut, M.A., Lesser, R.P. & Hart, J. Jr. 2002. Interactions between thalamic and cortical rhythms during semantic memory recall in human. Proc. Natl. Acad. Sci. U.S.A., 99, 6440-6443.

http://www.eurekalert.org/pub_releases/2002-05/uoaf-mi050902.php

Pictures show how nerve cells form connections to store memories

Scientists at the University of California, San Diego have produced dramatic images of brain cells forming temporary and permanent connections in response to various stimuli, illustrating for the first time the structural changes between neurons in the brain that, many scientists have long believed, take place when we store short-term and long-term memories.

Colicos, M.A., Collins, B.E., Sailor, M.J. & Goda, Y. 2001. Remodeling of Synaptic Actin Induced by Photoconductive Stimulation. Cell, 107 (5), 605-616.

http://ucsdnews.ucsd.edu/newsrel/science/mccell.htm

The neural bases of effective encoding

Failure to remember experiences often occurs not because the memory is hard to retrieve, but because it was not properly encoded in the first place. Imaging studies are beginning to give us a better idea of the neurocognitive processes that lead to more effective encoding.

Wagner, A.D. & Davachi, L. 2001. Cognitive neuroscience: Forgetting of things past. Current Biology, 11, R964-R967.

http://tinyurl.com/i87x

Imaging study confirms role of medial temporal lobe in memory consolidation

Lesions in the medial temporal lobe (MTL) typically produce amnesia characterized by the disproportionate loss of recently acquired memories. Such memory loss has been interpreted as evidence for a memory consolidation process guided by the MTL. A recent imaging study confirms this view by showing temporally graded changes in MTL activity in healthy older adults taking a famous faces remote memory test. Evidence for such temporally graded change in the hippocampal formation was mixed, suggesting it may participate only in consolidation processes lasting a few years. The entorhinal cortex (also part of the MTL) was associated with temporally graded changes extending up to 20 years, suggesting that it is the entorhinal cortex, rather than the hippocampal formation, that participates in memory consolidation over decades. The entorhinal cortex is damaged in the early stages of Alzheimer’s disease.

Haist, F., Gore, J.B. & Mao, H. 2001. Consolidation of human memory over decades revealed by functional magnetic resonance imaging. Nature neuroscience, 4 (11), 1139-1145.

http://www.nature.com/neurolink/v4/n11/abs/nn739.html

Crucial enzyme for consolidating long-term memories

Susumu Tonegawa and colleagues at the Massachusetts Institute of Technology and the Vollum Institute have released the first of a series of studies illuminating how short-term memories are turned into long-term ones via consolidation, how different types of learning occurs in unexpected ways, and how memory recall occurs. In this first study, the researchers eliminated the function of a single enzyme in a restricted memory-related region in the brains of mice, and thus showed that the enzyme is important in consolidating long-term memories. While this enzyme (calcium-calmodulin dependent kinase (CaMKIV)), has been implicated in the process of establishing long-term memories, previous research has been inconclusive because the techniques used to knock out the enzyme were so global. A series of behavioral experiments led the researchers to conclude that the CaMKIV pathway was primarily involved in memory consolidation and retention. However, memory consolidation was not completely extinguished, suggesting that there may be parallel signaling pathways involved in consolidation, or that there may have been incomplete knockout of CaMKIV activity.

Kang, H., Sun, L.D., Atkins, C.M., Soderling, T.R., Wilson, M.A. & Tonegawa, S. (2001). An Important Role of Neural Activity-Dependent CaMKIV Signaling in the Consolidation of Long-Term Memory. Cell, 106, 771-783.

http://www.eurekalert.org/pub_releases/2001-09/hhmi-rfe092001.php

Protein that allows information to be converted from short-term into lifelong memories identified

Scientists from UCLA and Johns Hopkins University have taken the first step in discovering how the brain, at the molecular and cellular level, converts short-term memories into permanent ones."Memories last different amounts of time," Frankland said. "You might remember a phone number for just a few minutes, for example, while certain childhood events will be remembered for a lifetime. Our study reveals the role of a protein that must be present in the cortex for information to be converted from short-term into lifelong memories."

Frankland, P.W., O'Brien, C., Ohno, M., Kirkwood, A. & Silva, A.J. 2001. α-CaMKII-dependent plasticity in the cortex is required for permanent memory. Nature, 411, 309-313.

http://www.eurekalert.org/pub_releases/2001-05/UNKN-BrfU-1505101.php

Specific molecule that helps brain reorganize in the face of new experiences targeted

For the first time scientists have been able to pinpoint a specific molecule that assists the brain to reorganize in the face of new experiences. Neuroscientists at the University of Rochester Medical Center found that genetically engineered mice that were challenged with new tasks improved their learning abilities. The team then boosted the amount of the molecule, nerve growth factor (NGF), in their brains, and found that the mice learned to run unfamiliar mazes more quickly than their unmodified counterparts.

The study was published in the Proceedings of the National Academy of Science.

http://www.eurekalert.org/pub_releases/2000-12/UoR-Simt-2612100.php

tags memworks: 

Skill Memory

Older news items (pre-2010) brought over from the old website

How long does it take to form a habit?

A study involving 96 people who were interested in forming a new habit such as eating a piece of fruit with lunch or doing a 15 minute run each day has found that in the early days, daily repetition sharply increased automaticity (the ease with which you do it) and then reached a plateau. On average, habits took 66 days to become as automatic as they’d ever be. However, there was a very wide variation (18 to 254 days) depending on the nature of the habit (more difficult habits, such as doing 50 sit-ups a day, showed a slower rate of steadier increase). There was also variability among individuals, with some showing ‘habit-resistance’. The good news is that missing a single day did not reduce the chance of forming a habit. The findings also point to the value of getting off to a good start.

Lally, P., Jaarsveld, C. H. M. V., Potts, H. W. W., & Wardle, J. (2009). How are habits formed: Modelling habit formation in the real world. European Journal of Social Psychology, Published online ahead of print. doi: 10.1002/ejsp.674.

http://ow.ly/CGUt

Imagining is as good as doing

A series of experiments in which some participants practiced identifying which line a central line was closest to, while others simply imagined the bisecting line's proximity based on an audio tone, found that both methods produced similar levels of perceptual learning. It has (understandably) been assumed that perceptual learning requires stimulus processing -- synapses firing in response to an actual physical cue. But this demonstrates that mental imagery is sufficient. The finding adds to a growing number of studies suggesting that thinking about something over and over again can be almost as good as doing it.

Tartaglia, E.M., Bamert, L., Mast, F.W. & Herzog, M.H. 2009. Human Perceptual Learning by Mental Imagery. Current Biology, Published online ahead of print 3 December 2009. 

http://www.physorg.com/news179067145.html

Magnetic brain stimulation improves skill learning

A study in which volunteers were trained for four days to track an apparently random target on a computer screen, in which random movement was interspersed with a repeated pattern not consciously perceived by the participants, found that those who received excitatory transcranial magnetic stimulation to the left dorsal premotor cortex were significantly better at tracking the repeating pattern than those who received inhibitory stimulation or sham stimulation. The findings support the view that the dorsal premotor cortex is important for learning motor skills, specifically through consolidation of the learned behavior.

Boyd, L.A. & Linsdell, M.A. 2009. Excitatory repetitive transcranial magnetic stimulation to left dorsal premotor cortex enhances motor consolidation of new skills. BMC Neuroscience, 10, 72doi:10.1186/1471-2202-10-72.

http://www.eurekalert.org/pub_releases/2009-07/bc-mbs070309.php

Motor skill learning may be enhanced by mild brain stimulation

In a study in which subjects practiced a challenging motor task over five consecutive days, those who received 20 minutes of a mild electrical current to the primary motor cortex improved significantly more that that of the control group, apparently through an effect on consolidation. Although both groups subsequently forgot the skill at about the same rate, those who had received the electrical stimulation still performed better after 3 months because they had learned the skill better. The findings hold promise for enhancing rehabilitation for people with traumatic brain injury, stroke and other conditions.

Reis, J. et al. 2009. Noninvasive cortical stimulation enhances motor skill acquisition over multiple days through an effect on consolidation. PNAS, 106, 1590-1595.

http://www.eurekalert.org/pub_releases/2009-01/nion-msl011609.php

Why it’s so hard to disrupt your routine

New research has added to our understanding of why we find it so hard to break a routine or overcome bad habits. The problem lies in the competition between the striatum and the hippocampus. The striatum is involved with habits and routines, for example, it records cues or landmarks that lead to a familiar destination. It’s the striatum that enables you to drive familiar routes without much conscious awareness. If you’re travelling an unfamiliar route however, you need the hippocampus, which is much ‘smarter’.  The mouse study found that when the striatum was disrupted, the mice had trouble navigating using landmarks, but they were actually better at spatial learning. When the hippocampus was disrupted, the converse was true. This may help us understand, and treat, certain mental illnesses in which patients have destructive, habit-like patterns of behavior or thought. Obsessive-compulsive disorder, Tourette syndrome, and drug addiction all involve abnormal function of the striatum. Cognitive-behavioral therapy may be thought of as trying to learn to use one of these systems to overcome and, ultimately, to re-train the other.

Lee, A.S. et al. 2008. A double dissociation revealing bidirectional competition between striatum and hippocampus during learning. Proceedings of the National Academy of Sciences, 105 (44), 17163-17168.

http://www.eurekalert.org/pub_releases/2008-10/yu-ce102008.php

Over-thinking and motor skills

Skilled athletes often maintain that thinking too much about executing a skill disrupts their performance. Now a study of 80 golfers has found that intermediate-skilled golfers asked to verbally describe a new putt after learning it took twice as many goes to sink their putts as similarly experienced golfers who weren’t asked to put their learning into words. On the other hand, golfers of lower skill benefited from such verbalization. The effect is thought to be similar to verbal overshadowing, an effect previously demonstrated for taste and appearance, where, for example, trying to describe a face interferes with subsequent recognition of that face.

Flegal, K.E. & Anderson, M.C. 2008. Overthinking skilled motor performance: Or why those who teach can't do. Psychonomic Bulletin & Review, 15, 927-932. 

http://www.physorg.com/news145638602.html

Passive learning imprints on the brain just like active learning

New research adds to other recent studies showing that observation can act like actual practice in acquiring new motor skills. In a study where participants played a video game in which they had to move in a particular sequence to match the position of arrows on the screen (similar to the popular Dance Revolution game), it was found that brain activity in the Action Observance Network (mostly in the inferior parietal and premotor cortices) was similar for dance sequences that were actively rehearsed daily for five days, and a different set of sequences that were passively observed for an equivalent amount of time, but declined for unfamiliar sequences.

Cross, E.S. et al. 2008. Sensitivity of the Action Observation Network to Physical and Observational Learning. Cerebral Cortex, Advance Access published on May 30, 2008. doi:10.1093/cercor/bhn083

http://www.eurekalert.org/pub_releases/2008-07/dc-drr071408.php

Songbirds offer clues to highly practiced motor skills in humans

A study of singing in the Bengalese finch has revealed information about motor skills that may benefit human performers and people needing motor rehabilitation. The tune of songbirds is a complex skill, achieved over a long period of practice as juveniles, and culminating in a highly stereotyped, stable song. But it turns out to be not as fixed as was thought. Adult songbirds, it seems, rely on auditory feedback to maintain their song. This study found that providing disruptive auditory feedback to a subset of the vocalizations almost immediately produced an appropriately targeted change in the bird's song. The study also found that really big changes could also be produced, but it had to be done incrementally, in small steps.

Tumer, E.C. & Brainard, M.S. 2007. Performance variability enables adaptive plasticity of 'crystallized' adult birdsong. Nature, 450, 1240-1244.

http://www.eurekalert.org/pub_releases/2007-12/uoc--soc122107.php

Language center executive organizer of action plans

Broca's area is the region in the brain traditionally known as the ‘language center’, however recent research has broadened that understanding. The most recent study reveals that this region, and its counterpart in the right hemisphere, becomes active when people are asked to organize plans of action — an activity that we must now distinguish from a simple action sequence, which didn’t require these regions. These regions appear to implement a specialized executive system controlling the selection and nesting of action segments in a hierarchical structure of behavioral plans. This general executive function may explain Broca’s key role in language production.

Koechlin, E. & Jubault, T. 2006. Broca's Area and the Hierarchical Organization of Human Behavior. Neuron, 50, 963–974.

http://www.eurekalert.org/pub_releases/2006-06/cp-wtb060806.php

Planning is goal-, not action-, oriented

Studies in which monkeys were asked to perform a complex task involving several discrete steps have revealed that the brain's "executive" center, in the lateral prefrontal cortex, plans behaviors not by specifying movements required for given actions, but rather the events that will result from those actions.

Mushiake, H. et al. 2006. Activity in the Lateral Prefrontal Cortex Reflects Multiple Steps of Future Events in Action Plans. Neuron, 50, 631–641.

http://www.eurekalert.org/pub_releases/2006-05/cp-tbe051106.php

People can learn motor skills by watching

Sure we learn by doing, but we also learn by watching. Recent imaging studies have shown that when we observe the actions of others, we activate the same neural circuitry responsible for planning and executing our own actions. Now a new study has demonstrated that such observation can actually facilitate motor learning. This occurred even when observers were distracted by another task (doing arithmetic) while watching, indicating that the process does not require conscious awareness. However, although there was no sign of muscle activity during the observation, the beneficial effects of observing were significantly reduced when the subjects were asked to perform unrelated arm movements during observation.

Mattar, A.A.G. & Gribble, P.L. 2005. Motor Learning by Observing. Neuron, 46 (1), 153–160.

http://www.eurekalert.org/pub_releases/2005-04/cp-pcl040105.php

Brain prefers 'automatic pilot' during learning

When people are asked to perform a classification or decision on an object, they become more efficient with repetition of the task. When subject's brains are imaged during such tasks, they show reduced activity -- called "neural priming" -- as the task is learned and performance improves. New research suggests that rather than this being due to the cortex refining its knowledge about the object being learned about (eliminating attributes of the object not needed in the task), the cortex is instead just refining learning of a particular response. Thus we become more rapid with repetition of a decision task simply because we are recovering our prior responses.
In the study, participants were asked to judge whether objects such as an acorn, a stroller, a bicycle pump or a shuttlecock were "bigger than a shoebox." After practicing this task, they were then asked if the objects were "smaller than a shoebox." If the brain's representation of the size of the object is what is being rapidly recovered with repetition, just changing the direction of the question from a 'bigger than' to a 'smaller than' question should not make a difference in performance. If, however, the brain is recovering earlier responses, then changing the direction of the question will make a considerable difference to performance – which it did.

Dobbins, I.G., Schnyer, D.M., Verfaellie, M. & Schacter, D.L. 2004. Cortical activity reductions during repetition priming can result from rapid response learning. Nature, 428, 316-319 (18 Mar 2004) Letters to Nature

http://www.eurekalert.org/pub_releases/2004-03/du-est030804.php

Reading verbs activates motor cortex areas

A new imaging study has surprised researchers by revealing that parts of the motor cortex respond when people do nothing more active than silently reading. However, the words read have to be action words. When such words are read, appropriate regions are activated – for example, reading “lick” will trigger blood flow in sites of the motor cortex associated with tongue and mouth movements. Moreover, activity also occurs in premotor brain regions that influence learning of new actions, as well as the language structures, Broca's area and Wernicke's area. The researchers suggest that these findings challenge the assumption that word meanings are processed solely in language structures – instead, our understanding of words depends on the integration of information from several interconnected brain structures that provide information about associated actions and sensations.

Hauk, O., Johnsrude, I. & Pulvermüller, F. 2004. Somatotopic Representation of Action Words in Human Motor and Premotor Cortex. Neuron, 41, 301-7.

http://www.sciencenews.org/20040207/fob2.asp

Learning a sequence with explicit knowledge of that sequence involves same

Imaging studies have found that sequence learning accompanied with awareness of the sequence activates entirely different brain regions than learning without awareness of the sequence. It has not been clear to what extent these two forms of learning (declarative vs procedural) are independent. A new imaging study devised a situation where subjects were simultaneously learning different sequences under implicit or explicit instructions, in order to establish whether, as many have thought, declarative learning prevents learning in procedural memory systems. It was found that procedural learning activated the left prefrontal cortex, left inferior parietal cortex, and right putamen. These same regions were also active during declarative learning. It appears that, in a well-controlled situation where procedural and declarative learning are occurring simultaneously, the same neural network for procedural learning is active whether that learning is or is not accompanied by declarative knowledge. Declarative learning, however, activates many additional brain regions.

Willingham, D.B., Salidis, J. & Gabrieli, J.D.E. 2003. Direct Comparison of Neural Systems Mediating Conscious and Unconscious Skill Learning. Journal of Neurophysiology, 88, 1451-1460.

Brain anticipates events to learn routines

A new study may help explain why “cognitive” practice of physical actions can be useful (e.g., sportsmen or musicians mentally “practicing” their skills). The study using macaque monkeys found that neurons in the visual cortex were more active when the monkeys anticipated the occurrence of predictable events. "These results show that as we practice and anticipate which events are going to happen, the brain is also preparing itself."

Ghose, G.M. &Maunsell, J.H.R. 2002. Attentional modulation in visual cortex depends on task timing. Nature, 419: 6907, 616-9.

http://www.eurekalert.org/pub_releases/2002-10/bcom-bae100802.php

Improving motor skills through sleep

People taught a simple motor sequence (to type a sequence of keys on a computer keyboard as quickly and accurately as possible) practised it for 12 minutes and were then re-tested 12 hours later. Those who practised in the morning and tested later that same day improved their performance by about 2%. Those trained in the evening and re-tested after a good night's sleep, however, improved by about 20%. The amount of improvement was directly correlated with the amount of Stage 2 (a stage of non-rapid eye movement or NREM) sleep experienced, particularly late in the night. "This is the part of a good night's sleep that many people will cut short by getting up early in the morning."

Laureys, S., Peigneux, P., Perrin, F. & Maquet, P. 2002. Sleep and Motor Skill Learning. Neuron, 35, 5-7.

http://www.eurekalert.org/pub_releases/2002-07/hms-pmp070102.php

New research into motor skills distinguishes between learning and performance

The cerebellum has long been associated with motor skills and coordination. A new study has shown that, although it is active when we are engaging in movement, it is not active when we are learning new motor skills. The findings suggest the cerebellum is involved in the improvement in performance gained through practice, rather than the initial learning of the motor sequence. This research may lead to a better understanding that ultimately sees the development of better rehabilitation strategies for patients with cerebellar disease. It also points to an intriguing difference between learning a motor skill and improving it.

Seidler, R.D., Purushotham, A., Kim, S.-G., Ugurbil, K., Willingham, D. & Ashe, J. 2002. Cerebellum Activation Associated with Performance Change but Not Motor Learning. Science, 296 (5575), 2043-6.

http://www.eurekalert.org/pub_releases/2002-06/vrcs-sop061302.php

The neural basis for motor learning

Learning happens when a brain cell gets stimulated in a way that reduces its ability to respond to a particular brain messenger called glutamate. In the cerebellum there are very large, strangely shaped brain cells called Purkinje cells that receive more connections than other types of neurons and fire 50 times per second even when you're sleeping. These cells are involved in simple motor learning processes. A recent study provides support for an earlier study that found there are fewer receptors for glutamate on the surface of neurons during long-term synaptic depression, by demonstrating that the other three possible causes for this reduced response to glutamate do not occur.

Linden, D.J. 2001.The expression of cerebellar LTD in culture is not associated with changes in AMPA-receptor kinetics, agonist affinity, or unitary conductance. Proc. Natl. Acad. Sci. USA, 98 (24), 14066-14071.

New motor skills consolidated during sleep

An imaging study that sheds light on the gain in performance observed during the day after learning a new task. Following training in a motor skill, certain brain areas appear to be reactivated during REM sleep, resulting in an optimization of the network that subtends the subject's visuo–motor response.

Laureys, S., Peigneux, P., Phillips, C., Fuchs,S., Degueldre, C., Aerts, J., Del Fiore,G., Petiau, C., Luxen, A., Van der Linden, M., Cleeremans, A., Smith, C. & Maquet, P. (2001). Experience-dependent changes in cerebral functional connectivity during human rapid eye movement sleep [Letter to Neuroscience]. Neuroscience, 105 (3), 521-525.

http://tinyurl.com/ix9b

Prospective Memory

Older news items (pre-2010) brought over from the old website

Why it’s so hard to disrupt your routine

New research has added to our understanding of why we find it so hard to break a routine or overcome bad habits. The problem lies in the competition between the striatum and the hippocampus. The striatum is involved with habits and routines, for example, it records cues or landmarks that lead to a familiar destination. It’s the striatum that enables you to drive familiar routes without much conscious awareness. If you’re travelling an unfamiliar route however, you need the hippocampus, which is much ‘smarter’.  The mouse study found that when the striatum was disrupted, the mice had trouble navigating using landmarks, but they were actually better at spatial learning. When the hippocampus was disrupted, the converse was true. This may help us understand, and treat, certain mental illnesses in which patients have destructive, habit-like patterns of behavior or thought. Obsessive-compulsive disorder, Tourette syndrome, and drug addiction all involve abnormal function of the striatum. Cognitive-behavioral therapy may be thought of as trying to learn to use one of these systems to overcome and, ultimately, to re-train the other.

[931] Lee, A. S., Duman R. S., & Pittenger C.
(2008).  A double dissociation revealing bidirectional competition between striatum and hippocampus during learning.
Proceedings of the National Academy of Sciences. 105(44), 17163 - 17168.

http://www.eurekalert.org/pub_releases/2008-10/yu-ce102008.php

Brain's voluntary chain-of-command ruled by not 1 but 2 captains

Previous research has shown a large number of brain regions (39) that are consistently active when people prepare for a mental task. It’s been assumed that all these regions work together under the command of one single region. A new study, however, indicates that there are actually two independent networks operating. The cingulo-opercular network (including the dorsal anterior cingulate/medial superior frontal cortex, anterior insula/frontal operculum, and anterior prefrontal cortex) is linked to a "sustain" signal — it turns on at the beginning, hums away constantly during the task, then turns off at the end. In contrast, the frontoparietal network (including the dorsolateral prefrontal cortex and intraparietal sulcus) is active at the start of mental tasks and during the correction of errors. The findings may help efforts to understand the effects of brain injury and develop new strategies to treat such injuries.
Dosenbach, N.U.F. et al. 2007. Distinct brain networks for adaptive and stable task control in humans. Proceedings of the National Academy of Sciences, 104 (26), 11073-11078.

http://www.physorg.com/news101478606.html

Planning is goal-, not action-, oriented

Studies in which monkeys were asked to perform a complex task involving several discrete steps have revealed that the brain's "executive" center, in the lateral prefrontal cortex, plans behaviors not by specifying movements required for given actions, but rather the events that will result from those actions.

Mushiake, H. et al. 2006. Activity in the Lateral Prefrontal Cortex Reflects Multiple Steps of Future Events in Action Plans. Neuron, 50, 631–641.

http://www.eurekalert.org/pub_releases/2006-05/cp-tbe051106.php

Time really does fly when you’re busy

We all know that time goes faster when we’re busy, but though scientists have long tried to prove a link between attention and time estimation, it has been difficult to design an experimental manipulation that only manipulates attention and not other, potentially confounding variables. But now, it seems, two researchers have managed to do it – and the finding is clear. Results showed that an attentionally demanding search task produced a large underestimation of time, and that as the amount of attention increased, so did the underestimation of time. Note that the study involved prospective estimates of time (participants knew in advance that they would be asked how long the task took), rather than retrospective.

Chaston, A. & Kingstone, A. 2004. Time estimation: The effect of cortically mediated attention. Brain and Cognition, 55 (2), 286-289.

http://www.eurekalert.org/pub_releases/2004-08/uoa-spt080604.php

More light shed on how episodic memories are formed

A rat study has revealed more about the workings of the hippocampus. Previous studies have identified “place cells” in the hippocampus – neurons which become more active in response to a particular spatial location. Activity in the hippocampus while rats searched for food in a maze where the starting and ending point was varied, has found that, while some cells signaled location alone, others were also sensitive to recent or impending events – i.e., activation depended upon where the rat had just been or where it intended to go. This finding helps us understand how episodic memories are formed – how, for example, a spatial location can trigger a reminder of an intended action at a particular time, but not others.

Suzuki, W. A. (2003). Episodic Memory Signals in the Rat Hippocampus. Neuron, 40(6), 1055–1056. doi:10.1016/S0896-6273(03)00806-7

http://www.eurekalert.org/pub_releases/2003-12/msh-ta121503.php

Imaging confirms role of frontal lobes in planning

New research provides the first neuro-imaging evidence that the brain's frontal lobes play a critical role in planning and choosing actions.

Connolly, J.D., Goodale, M.A., Menon R.S. & Munoz, D.P. 2002. Human fMRI evidence for the neural correlates of preparatory set.Nature Neuroscience, 5 (12),1345–1352.

Role of prefrontal cortical regions in goal-directed behavior

Goal-directed behaviour depends on keeping relevant information in mind (working memory) and irrelevant information out of mind (behavioural inhibition or interference resolution). Prefrontal cortex is essential for both working memory and for interference resolution, but it is unknown whether these two mental abilities are mediated by common or distinct prefrontal regions. An imaging study found there was a high degree of overlap between the regions activated by load and interference, while no region was activated exclusively by interference. The findings suggest that, within the circuitry engaged by this task, some regions are more critically involved in the resolution of interference whereas others are more involved in the resolution of an increase in load.

Bunge, S.A., Ochsner, K.N., Desmond, J.E., Glover, G.H. & Gabrieli J.D.E. (2001). Prefrontal regions involved in keeping information in and out of mind. Brain, 124 (10), 2074-2086.

tags memworks: 

Autobiographical Memory

Older news items (pre-2010) brought over from the old website

The role of emotion

see more at Emotion, Stress & anxiety, and Fear & trauma

Life-defining events remembered more favorably

A study has found that when people feel an event has had a large impact on them, they downplay the negative and emphasize the positive. For such significant events, when asked to reflect on negative events, people reported less negative emotion and more positive emotion compared to how they recalled feeling at the time. Similarly, for positive events, people reported more positive emotion and less negative emotion compared to how they recalled feeling at the time.

Conway, M. & Wood, W-J. 2006. Subjective Impact, Meaning Making, and Current and Recalled Emotions for Self-Defining Memories. Journal of Personality, 74, 811-

http://www.eurekalert.org/pub_releases/2006-05/bpl-omw051606.php

Memories of crime stories influenced by racial stereotypes

The influence of stereotypes on memory, a well-established phenomenon, has been demonstrated anew in a study concerning people's memory of news photographs. In the study, 163 college students (of whom 147 were White) examined one of four types of news stories, all about a hypothetical Black man. Two of the stories were not about crime, the third dealt with non-violent crime, while the fourth focused on violent crime. All four stories included an identical photograph of the same man. Afterwards, participants reconstructed the photograph by selecting from a series of facial features presented on a computer screen. It was found that selected features didn’t differ from the actual photograph in the non-crime conditions, but for the crime stories, more pronounced African-American features tended to be selected, particularly so for the story concerning violent crime. Participants appeared largely unaware of their associations of violent crime with the physical characteristics of African-Americans.

Oliver, M.B., Jackson, R.L.II., Moses, N.N. & Dangerfield, C.L. 2004. The Face of Crime: Viewers' Memory of Race-Related Facial Features of Individuals Pictured in the News. Journal of Communication, 54, 88-104.

http://www.eurekalert.org/pub_releases/2004-05/ps-rmo050504.php

How memory helps make life pleasant

Surveys consistently show that people are generally happy with their lives. A review of research into autobiographical memory suggests why - human memory is biased toward happiness. Across 12 studies conducted by five different research teams, people of different racial and ethnic backgrounds and of different ages consistently reported experiencing more positive events in their lives than negative events, suggesting that pleasant events do in fact outnumber unpleasant events because people seek out positive experiences and avoid negative ones. Our memory also treats pleasant emotions differently from unpleasant emotions. Pleasant emotions appear to fade more slowly from our memory than unpleasant emotions. This is not repression; people do remember negative events, they just remember them less negatively. Among those with mild depression, however, unpleasant and pleasant emotions tend to fade evenly.

Walker, W.R., Skowronski, J.J. & Thompson, C.P. 2003. Life Is Pleasant -- and Memory Helps to Keep It That Way! Review of General Psychology, 7(2),203-10.

http://www.eurekalert.org/pub_releases/2003-06/apa-rtg060203.php

Suppressing your expression of emotion affects your memory for the event

The way people go about controlling their reactions to emotional events affects their memory of the event. In a series of experiments designed to assess the effect of suppressing the expression of emotion, it was found that, when people were shown a video of an emotional event and instructed not to let their emotions show, they had poorer memory for what was said and done than did those people who were given no such instructions. However, when shown slides of people who had been injured, people in both groups were equally good at picking which in an array of subtly different versions of each slide had been shown earlier - but when prompted to recall information that had been presented verbally with each slide, those in the suppression group again remembered fewer details. People who were asked to adopt the neutral attitude of a medical profession however, performed better than the control group on nonverbal recall, indicating the regulation of emotions via reappraisal was not associated with any memory impairment. These experimental results were supported by a naturalistic study.

Richards, J.M. & Gross, J.J. (2000). Emotion Regulation and Memory: The Cognitive Costs of Keeping One's Cool. Journal of Personality and Social Psychology, 79 (3), 410-424.

http://www.sciencedaily.com/releases/2000/09/000913203335.htm

Where are our personal experiences stored in the brain?

Brain hub links music and autobiographical memory

We all know that songs from our youth can evoke strong autobiographical memories. Now a new study explains why. Brain scans of students listening to excerpts of 30 different popular tunes found that a student recognized on average about 17 of the 30 excerpts, and of these, about 13 were moderately or strongly associated with an autobiographical memory. The strength of that memory was reflected in the amount of activity in the upper (dorsal) part of the medial prefrontal cortex, a region critically involved in integrating sensory information with self-knowledge and the retrieval of autobiographical information. Moreover, mapping the tones of each excerpt showed that the brain was tracking these tonal progressions in the same region as it was experiencing the memories: in the dorsal part of the medial prefrontal cortex, and the regions immediately adjacent to it. Again, the stronger the autobiographical memory, the greater the tracking activity. The finding explains why memory for autobiographically important music lingers in Alzheimer’s sufferers — the area is one of the last to be affected.

Janata, P. 2009. The Neural Architecture of Music-Evoked Autobiographical Memories. Cerebral Cortex, Advance Access published on February 24. Full text available at http://cercor.oxfordjournals.org/cgi/content/abstract/bhp008   

http://www.physorg.com/news154683105.html
http://www.eurekalert.org/pub_releases/2009-02/uoc--sfb021809.php

Long-term storage of autobiographical memories

By studying in detail the ability of patients with selective brain damage to recall events in their past, researchers have helped settle a long-standing controversy about whether long-term memory of one's personal experiences continue to be stored in the medial temporal lobe, or whether they gradually become independent of this area. The evidence from this new study suggests that autobiographical memories gradually become distributed throughout the neocortex.

Bayley, P.J., Gold, J.J., Hopkins, R.O. & Squire, L.R. 2005. The Neuroanatomy of Remote Memory. Neuron, 46, 799–810.

http://www.eurekalert.org/pub_releases/2005-06/cp-wlm052605.php

What happens in the brain when we remember our own past?

A new imaging study has managed to distinguish between two types of autobiographical memory — the “facts” of our lives (e.g., knowing that you attended your cousin’s wedding last year), and the experiences of our lives (e.g., remembering traveling to the wedding, the events and people). As with much autobiographical memory research, the study used a diary-type procedure, whereby volunteers spent several months recording the events of their lives on a micro cassette recorder, as well as personal facts of their lives. These recordings were then played back to the volunteers while their brains were being scanned with fMRI. The results showed that the two types of autobiographical memory engaged different parts of the brain, even when the memories concerned the same contents. Recall of personal episodic memories more strongly engaged parts of the frontal lobes involved in self-awareness, as well as areas involved in visual memory.

Levine, B., Turner, G.R., Tisserand, D., Hevenor, S.J., Graham, S.J. & McIntosh, A.R. 2004. The Functional Neuroanatomy of Episodic and Semantic Autobiographical Remembering: A Prospective Functional MRI Study. Journal of Cognitive Neuroscience, 16(9), 1633-1646.

http://www.eurekalert.org/pub_releases/2004-11/bcfg-whi111604.php

New technique sheds light on autobiographical memory

A new technique for studying autobiographical memory has revealed new findings about autobiographical memory, and may prove useful in studying age-related cognitive impairment. Previous inconsistencies between controlled laboratory studies of memory (typically, subjects are asked to remember items they have previously seen in the laboratory, such as words presented on a computer screen) and studies of autobiographical memory have seemed to indicate that the brain may function differently in the two processes. However, such differences might instead reflect how the memories are measured. In an effort to provide greater control over the autobiographical memories, volunteer subjects were given cameras and instructed to take pictures of campus scenes. The subjects were also instructed to remember the taking of each picture as an individual event, noting the physical conditions and their psychological state, such as their mood and associations with the subject of the images. The subjects were then shown a selection of campus photos they had not taken. While their brains were scanned, they were then shown a mix of their own photos with those they had not taken, and asked to indicate whether each photo was new, seen earlier in the lab, or one they had taken themselves. The researchers found that recalling the autobiographical memories activated many of the same brain areas as laboratory memories (the medial temporal lobe and the prefrontal cortex); however, they also activated brain areas associated with "self-referential processing" (processing information about one's self), and regions associated with retrieval of visual and spatial information, as well as showing a higher level of activity in the recollection areas in the hippocampus.

Cabeza, R., Prince, S. E., Daselaar, S. M., Greenberg, D. L., Budde, M., Dolcos, F., … Rubin, D. C. (2004). Brain Activity during Episodic Retrieval of Autobiographical and Laboratory Events: An fMRI Study using a Novel Photo Paradigm. Journal of Cognitive Neuroscience, 16(9), 1583–1594. doi:10.1162/0898929042568578

http://www.eurekalert.org/pub_releases/2004-09/du-blm092904.php

The chunking of our lives: the brain "sees" life in segments

We talk about "chunking" all the time in the context of memory. But the process of breaking information down into manageable bits occurs, it seems, right from perception. Magnetic resonance imaging reveals that when people watched movies of common, everyday, goal-directed activities (making the bed, doing the dishes, ironing a shirt), their brains automatically broke these continuous events into smaller segments. The study also identified a network of brain areas that is activated during the perception of boundaries between events. "The fact that changes in brain activity occurred during the passive viewing of movies indicates that this is how we normally perceive continuous events, as a series of segments rather than a dynamic flow of action."

Zacks, J.M., Braver, T.S., Sheridan, M.A., Donaldson, D.I., Snyder, A.Z., Ollinger, J.M., Buckner, R.L. & Raichle, M.E. 2001. Human brain activity time-locked to perceptual event boundaries. Nature Neuroscience, 4(6), 651-5.

http://www.eurekalert.org/pub_releases/2001-07/aaft-bp070201.php

Amygdala may be critical for allowing perception of emotionally significant events despite inattention

We choose what to pay attention to, what to remember. We give more weight to some things than others. Our perceptions and memories of events are influenced by our preconceptions, and by our moods. Researchers at Yale and New York University have recently published research indicating that the part of the brain known as the amygdala is responsible for the influence of emotion on perception. This builds on previous research showing that the amygdala is critically involved in computing the emotional significance of events. The amygdala is connected to those brain regions dealing with sensory experiences, and the theory that these connections allow the amygdala to influence early perceptual processing is supported by this research. Dr. Anderson suggests that “the amygdala appears to be critical for the emotional tuning of perceptual experience, allowing perception of emotionally significant events to occur despite inattention.”

Anderson, A.K. & Phelps, E.A. 2001. Lesions of the human amygdala impair enhanced perception of emotionally salient events. Nature, 411, 305-309.

http://www.eurekalert.org/pub_releases/2001-05/NYU-Infr-1605101.php

Why some people remember events better than others

Gene linked to poor episodic memory

Brain derived neurotrophic factor (BDNF) plays a key role in neuron growth and survival and, it now appears, memory. We inherit two copies of the BDNF gene - one from each parent - in either of two versions. Slightly more than a third inherit at least one copy of a version nicknamed "met," which the researchers have now linked to poorer memory. Those who inherit the “met” gene appear significantly worse at remembering events that have happened to them, probably as a result of the gene’s effect on hippocampal function. Most notably, those who had two copies of the “met” gene scored only 40% on a test of episodic (event) memory, while those who had two copies of the other version scored 70%. Other types of memory did not appear to be affected. It is speculated that having the “met” gene might also increase the risk of disorders such as Alzheimer’s and Parkinson's.

Egan, M.F., Kojima, M., Callicott, J.H., Goldberg, T.E., Kolachana, B.S., Bertolino, A., Zaitsev, E., Gold, B., Goldman, D., Dean, M., Lu, B. & Weinberger, D.R. 2003. The BDNF val66met Polymorphism Affects Activity-Dependent Secretion of BDNF and Human Memory and Hippocampal Function. Cell, 112, 257-269.

http://www.nih.gov/news/pr/jan2003/nimh-23.htm
http://www.eurekalert.org/pub_releases/2003-01/niom-hga012203.php
http://news.bbc.co.uk/1/hi/health/2687267.stm

Childhood "amnesia" linked to vocabulary

"Childhood amnesia" is the term given to the well-known phenomenon of our almost complete lack of memory for the experiences of our very early childhood. Exactly why it occurs is long been a subject of debate. New research suggests the answer may lie in the very limited vocabulary of very young children. A study of 2- and 3-year-old children found that children can only describe memories of events using words they knew when the experience occurred. When asked about the experimental situation (involving a "magic shrinking machine") a year later, the children easily remembered how to operate the device, but were only able to describe the machine in words they knew when they first learned how to operate it.

Simcock, G. & Hayne, H. 2002. Breaking the Barrier? Children Fail to Translate Their Preverbal Memories Into Language. Psychological Science, 13 (3), 225-231.

Left-handers may be better at remembering events

A recent study that compared episodic memory (for events) and implicit memory (for facts) concluded that the two hemispheres of the brain work together to help us remember events, while facts are processed in one hemisphere alone. It seems that people whose brains' halves work together more actively (people with left-handedness in their families - although not necessarily left-handed themselves) remember events better than they remember facts. These findings also help explain why children don't remember events until about age 4, when the fibers connecting the hemispheres fully develop.

Christman, S.D. & Propper, R.E. (2001). Superior Episodic Memory Is Associated With Interhemispheric Processing. Neuropsychology, 15 (4), 607–616.

http://www.apa.org/releases/leftymemory.html

Cultural differences in autobiographical memory

American adults and preschool children recall their personal memories in a way that is consistently different from the way indigenous Chinese do, according to recent study. "Americans often report lengthy, specific, emotionally elaborate memories that focus on the self as a central character. Chinese tend to give brief accounts of general routine events that center on collective activities and are often emotionally neutral."From an earlier study (published in Memory, Vol. 8, 2000), it is thought that these differences in remembering (with their implications for sense of self) reflect the different conversational styles between mother and child found in these two cultures.

Wang, Q. (2001). Culture effects on adults’ earliest childhood recollection and self-description: Implications for the relation between memory and the self. Journal of Personality and Social Psychology, 81(2), 220–233. doi:10.1037/0022-3514.81.2.220

http://www.eurekalert.org/pub_releases/2001-06/aaft-ach062601.php

How familiarity can mislead

People remember prices more easily if they have fewer syllables

The phonological loop — an important component of working memory —can only hold 1.5 to 2 seconds of spoken information. For that reason, faster speakers have an advantage over slower speakers. Now a consumer study reveals that every extra syllable in a product's price decreases its chances of being remembered by 20%. Thus, people who shorten the number of syllables (e.g. read 5,325 as 'five three two five' as opposed to 'five thousand three hundred and twenty five') have better recall. However, since we store information both verbally and visually, it’s also the case that unusual looking prices, such as $8.88, are recalled better than typical looking prices.

Vanhuele, M., Laurent, G., Dreze, X. & Calder, B. 2006. Consumers' Immediate Memory for Prices. Journal of Consumer Research, in press.

http://www.sciencedaily.com/releases/2006/06/060623001231.htm
http://www.eurekalert.org/pub_releases/2006-06/uocp-prp062206.php

Increasing consumer preferences by manipulating memory

In two experiments, people who had to solve an anagram before seeing a target brand, they were more likely to claim to have seen the brand before, and to prefer it over competing brands.

Kronlund, A. & Bernstein, D.M. 2006. Unscrambling words increases brand name recognition and preference. Applied Cognitive Psychology, 20(5), 681–687.

http://www.eurekalert.org/pub_releases/2006-06/jws-icp062606.php

Older adults more likely to "remember" misinformation

In a study involving older adults (average age 75) and younger adults (average age 19), participants studied lists of paired related words, then viewed new lists of paired words, some the same as before, some different, and some with only one of the two words the same. In those cases, the "prime" word, which was presented immediately prior to the test, was plausible but incorrect. The older adults were 10 times more likely than young adults to accept the wrong word and falsely "remember" earlier studying that word. This was true even though older adults had more time to study the list of word pairs and attained a performance level equal to that of the young adults. Additionally, when told they had the option to "pass" when unsure of an answer, older adults rarely used the option. Younger adults did, greatly reducing their false recall. The findings reflect real-world reports of a rising incidence of scams perpetrated on the elderly, which rely on the victim’s poor memory and vulnerability to the power of suggestion.

Jacoby, L.L., Bishara, A.J., Hessels, S. & Toth, J.P. 2005. Aging, Subjective Experience, and Cognitive Control: Dramatic False Remembering by Older Adults. Journal of Experimental Psychology: General, 134 (2)

http://www.eurekalert.org/pub_releases/2005-05/apa-gmc051005.php

Repeated product warnings are remembered as product recommendations

Warnings about particular products may have quite the opposite effect than intended. Because we retain a familiarity with encountered items far longer than details, the more often we are told a claim about a consumer item is false, the more likely we are to accept it as true a little further down the track. Research also reveals that older adults are more susceptible to this error. It is relevant to note that in the U.S. at least, some 80% of consumer fraud victims are over 65.

Skurnik, I., Yoon, C., Park, D.C. & Schwarz, N. 2005. How Warnings About False Claims Become Recommendations. Journal Of Consumer Research, 31

http://www.eurekalert.org/pub_releases/2005-03/uocp-nrr032905.php

You may not be able to recall it, but it influences you anyway

“Forgetting” doesn’t mean the memory is erased from your brain. “Forgotten” information may in fact influence you more than it would if it hadn’t been forgotten — because you’re unaware of the influence. This somewhat alarming possibility has been raised by a recent study in which college students studied lists of nonfamous and famous names. Some participants were told to remember the nonfamous names, while the others were told to forget them. Later, both groups were asked to judge whether or not a name was famous from a mixed list of famous and nonfamous names. Those who were told to forget misidentified more nonfamous names as famous than those who had been told to remember.
Such a judgment is of course made on the basis of the familiarity of the name. It is exposure to an item that affects its familiarity – not whether or not you consciously remember it. By telling the participants to “forget” what they’d seen, the experimenters were removing the participants’ awareness of the source of the familiarity, not the familiarity itself.

Bjork, E.L. & Bjork, R.A. 2003. Intentional Forgetting Can Increase, Not Decrease, Residual Influences of To-Be-Forgotten Information. Journal of Experimental Psychology: Learning, Memory, and Cognition, 29 (4), 524–531.

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