Grey Matter

In 2013 I reported briefly on a pilot study showing that “super-agers” — those over 80 years old who have the brains and cognitive powers more typical of people decades younger — had an unusually large anterior cingulate cortex, with four times as many von Economo neurons.

The ACC is critical for cognitive control, executive function, and motivation. Von Economo neurons have been linked to social intelligence, being found (as yet) only in humans, great apes, whales and dolphins, with a reduction being found in frontotemporal dementia and autism.

A follow-up to that study has now been reported, confirming the larger ACC, and greater amount of von Economo neurons.

The study involved 31 super-agers, 21 more typical older adults, and 18 middle-aged adults (aged 50-60). Imaging revealed a region of the ACC in the right hemisphere in the super-agers was not only significantly thicker than the 'normal' older adults, but also larger than that of the middle-aged adults. Post-mortem analysis of 5 of the super-agers found that their ACC had 87% less tau tangles (one of the hallmarks of Alzheimer's) than 5 'normal' age-matched controls, and 92% less than that of 5 individuals with MCI. The density of von Economo neurons was also significantly higher.

Whether or not super-agers are born or made is still unknown (I'm picking a bit of both), but it's intriguing to note my recent report that people who frequently use several media devices at the same time had smaller grey matter density in the anterior cingulate cortex than those who use just one device occasionally.

I'd be interested to know the occupational and life-history of these super-agers. Did they lead lives in which they nurtured their powers of prolonged concentration? Or perhaps they belong to that other select group: the one-in-forty who can truly multitask.

[3880] Gefen, T., Peterson M., Papastefan S. T., Martersteck A., Whitney K., Rademaker A., et al.
(2015).  Morphometric and Histologic Substrates of Cingulate Integrity in Elders with Exceptional Memory Capacity.
The Journal of Neuroscience. 35(4), 1781 - 1791.

Three recent studies point to the impact of social media and multiple device use on learning and cognitive control.

College students take years to learn to manage their social media so it doesn't impact their grades

A survey of 1,649 college students has found that freshmen average a total of two hours a day on Facebook, of which over an hour is spent also doing schoolwork, and that time spent on Facebook had a negative impact on their grade point average. For sophomores and juniors, only time spent using Facebook while doing schoolwork affected their GPA.

Seniors spent the least time on Facebook, the least time multitasking on Facebook, and their time on Facebook didn't affect their grades.

It's suggested that the difference between the year-groups has to do with the way the students interact with Facebook, and in particular, the students' ability to self-regulate.

Internet use during class impacts grades no matter how smart you are

An investigation into non-academic Internet use during an introductory psychology class has found that all students, regardless of their intellectual ability, were negatively affected by greater Internet use, with lower exam scores the more they used the Internet.

Not surprisingly (given other research showing that students are notoriously bad at appreciating good strategies or recognizing poor ones), the students themselves discounted such effects on their learning.

The study involved some 500 students, and used self-reports of internet use.

Given that this is an introductory class, we can safely assume most are freshmen.

Brain scans reveal 'gray matter' differences in media multitaskers

A brain imaging study involving 75 adults has found that, independent of individual personality traits, people who frequently use several media devices at the same time had smaller grey matter density in the anterior cingulate cortex than those who use just one device occasionally. Functional connectivity between the ACC and the precuneus was also negatively affected.

The ACC is critical for cognitive and emotional control.

While it is possible that people with a smaller ACC are more likely to engage in such multitasking, the findings are consistent with other research showing that building expertise also builds gray matter in the relevant brain region (e.g., London taxi drivers building up the part of their hippocampus that deals with navigation), while gray matter can also shrink with disuse.

The findings are also consistent with evidence that individuals who engage in heavier media-multitasking perform more poorly on cognitive control tasks and exhibit more socio-emotional difficulties.

There's both positive and negative news in these reports:

positive, that students can eventually learn how to control their media multitasking (though the question occurs: is there a correlation between the students who drop out and those who can't learn the requisite cognitive control?)

negative, that failing to learn the requisite control may push the student into a negative feedback cycle, with their cognitive control network being eroded the more they continue to media multitask.

The negative scenario becomes even more likely for some individuals when you realize that those with the poorest control are unlikely to recognize their problem:

Poor multitaskers don't realize it

In 2013, I reported that college students who scored highest in multitasking ability were least likely to multitask, while those who scored lowest were most likely to engage in it. Last year, another study came out telling us that, while people generally realize that multitasking impairs performance, those who are worse at it don't realize it.

The study involved 69 volunteers who were given a visual tracking task, in which they had to keep a mouse cursor within a small target that moved erratically around a circular track. They also separately performed an auditory n-back task (a challenging working memory task). Before being asked to perform both tasks at the same time, they were asked to predict how much their performance would be affected.

Most people overestimated how much their performance would suffer. However, there was no correlation at all between individual predictions and performance, and those who were most affected showed no awareness that they were poorer than average at multitasking.

[3870] Junco, R.
(2015).  Student class standing, Facebook use, and academic performance.
Journal of Applied Developmental Psychology. 36, 18 - 29.

[3873] Ravizza, S. M., Hambrick D. Z., & Fenn K. M.
(2014).  Non-academic internet use in the classroom is negatively related to classroom learning regardless of intellectual ability.
Computers & Education. 78, 109 - 114.

[3872] Loh, K. Kee, & Kanai R.
(2014).  Higher Media Multi-Tasking Activity Is Associated with Smaller Gray-Matter Density in the Anterior Cingulate Cortex.
PLoS ONE. 9(9), 

[3868] Finley, J. R., Benjamin A. S., & McCarley J. S.
(2014).  Metacognition of multitasking: How well do we predict the costs of divided attention?.
Journal of Experimental Psychology: Applied. 20(2), 158 - 165.

I’ve reported before on how London taxi drivers increase the size of their posterior hippocampus by acquiring and practicing ‘the Knowledge’ (but perhaps at the expense of other functions). A new study in similar vein has looked at the effects of piano tuning expertise on the brain.

The study looked at the brains of 19 professional piano tuners (aged 25-78, average age 51.5 years; 3 female; 6 left-handed) and 19 age-matched controls. Piano tuning requires comparison of two notes that are close in pitch, meaning that the tuner has to accurately perceive the particular frequency difference. Exactly how that is achieved, in terms of brain function, has not been investigated until now.

The brain scans showed that piano tuners had increased grey matter in a number of brain regions. In some areas, the difference between tuners and controls was categorical — that is, tuners as a group showed increased gray matter in right hemisphere regions of the frontal operculum, the planum polare, superior frontal gyrus, and posterior cingulate gyrus, and reduced gray matter in the left hippocampus, parahippocampal gyrus, and superior temporal lobe. Differences in these areas didn’t vary systematically between individual tuners.

However, tuners also showed a marked increase in gray matter volume in several areas that was dose-dependent (that is, varied with years of tuning experience) — the anterior hippocampus, parahippocampal gyrus, right middle temporal and superior temporal gyrus, insula, precuneus, and inferior parietal lobe — as well as an increase in white matter in the posterior hippocampus.

These differences were not affected by actual chronological age, or, interestingly, level of musicality. However, they were affected by starting age, as well as years of tuning experience.

What these findings suggest is that achieving expertise in this area requires an initial development of active listening skills that is underpinned by categorical brain changes in the auditory cortex. These superior active listening skills then set the scene for the development of further skills that involve what the researchers call “expert navigation through a complex soundscape”. This process may, it seems, involve the encoding and consolidating of precise sound “templates” — hence the development of the hippocampal network, and hence the dependence on experience.

The hippocampus, apart from its general role in encoding and consolidating, has a special role in spatial navigation (as shown, for example, in the London cab driver studies, and the ‘parahippocampal place area’). The present findings extend that navigation in physical space to the more metaphoric one of relational organization in conceptual space.

The more general message from this study, of course, is confirmation for the role of expertise in developing specific brain regions, and a reminder that this comes at the expense of other regions. So choose your area of expertise wisely!

Why is diabetes associated with cognitive impairment and even dementia in older adults? New research pinpoints two molecules that trigger a cascade of events that end in poor blood flow and brain atrophy.

The study involved 147 older adults (average age 65), of whom 71 had type 2 diabetes and had been taking medication to manage it for at least five years. Brain scans showed that the diabetic patients had greater blood vessel constriction than the age- and sex-matched controls, and more brain atrophy. The reduction in brain tissue was most marked in the grey matter in the parietal and occipital lobes and cerebellum. Research has found that, at this age, while the average brain shrinks by about 1% annually, a diabetic brain might shrink by as much as 15%. Diabetics also had more white matter hyperintensities in the temporal, parietal and occipital lobes.

Behaviorally, the diabetics also had greater depression, slower walking, and executive dysfunction.

The reduced performance of blood vessels (greater vasoconstriction, blunted vasodilatation), and increased brain atrophy in the frontal, temporal, and parietal lobes, was associated with two adhesion molecules – sVCAM and sICAM. White matter hyperintensities were not associated with the adhesion molecules, inflammatory markers, or blood vessel changes.

It seems that the release of these molecules, probably brought about by chronic hyperglycemia and insulin resistance, produces chronic inflammation, which in turn brings about constricted blood vessels, reduced blood flow, and finally loss of neurons. The blood vessel constriction and the brain atrophy were also linked to higher glucose levels.

The findings suggest that these adhesion molecules provide two biomarkers of vascular health that could enable clinicians to recognize impending brain damage, that could then perhaps be prevented.

The findings also add weight to the growing evidence that diabetes management is crucial in preventing cognitive decline.

The evidence that adult brains could grow new neurons was a game-changer, and has spawned all manner of products to try and stimulate such neurogenesis, to help fight back against age-related cognitive decline and even dementia. An important study in the evidence for the role of experience and training in growing new neurons was Maguire’s celebrated study of London taxi drivers, back in 2000.

The small study, involving 16 male, right-handed taxi drivers with an average experience of 14.3 years (range 1.5 to 42 years), found that the taxi drivers had significantly more grey matter (neurons) in the posterior hippocampus than matched controls, while the controls showed relatively more grey matter in the anterior hippocampus. Overall, these balanced out, so that the volume of the hippocampus as a whole wasn’t different for the two groups. The volume in the right posterior hippocampus correlated with the amount of experience the driver had (the correlation remained after age was accounted for).

The posterior hippocampus is preferentially involved in spatial navigation. The fact that only the right posterior hippocampus showed an experience-linked increase suggests that the right and left posterior hippocampi are involved in spatial navigation in different ways. The decrease in anterior volume suggests that the need to store increasingly detailed spatial maps brings about a reorganization of the hippocampus.

But (although the experience-related correlation is certainly indicative) it could be that those who manage to become licensed taxi drivers in London are those who have some innate advantage, evidenced in a more developed posterior hippocampus. Only around half of those who go through the strenuous training program succeed in qualifying — London taxi drivers are unique in the world for being required to pass through a lengthy training period and pass stringent exams, demonstrating their knowledge of London’s 25,000 streets and their idiosyncratic layout, plus 20,000 landmarks.

In this new study, Maguire and her colleague made a more direct test of this question. 79 trainee taxi drivers and 31 controls took cognitive tests and had their brains scanned at two time points: at the beginning of training, and 3-4 years later. Of the 79 would-be taxi drivers, only 39 qualified, giving the researchers three groups to compare.

There were no differences in cognitive performance or brain scans between the three groups at time 1 (before training). At time 2 however, when the trainees had either passed the test or failed to acquire the Knowledge, those trainees that qualified had significantly more gray matter in the posterior hippocampus than they had had previously. There was no change in those who failed to qualify or in the controls.

Unsurprisingly, both qualified and non-qualified trainees were significantly better at judging the spatial relations between London landmarks than the control group. However, qualified trainees – but not the trainees who failed to qualify – were worse than the other groups at recalling a complex visual figure after 30 minutes (see here for an example of such a figure). Such a finding replicates previous findings of London taxi drivers. In other words, their improvement in spatial memory as it pertains to London seems to have come at a cost.

Interestingly, there was no detectable difference in the structure of the anterior hippocampus, suggesting that these changes develop later, in response to changes in the posterior hippocampus. However, the poorer performance on the complex figure test may be an early sign of changes in the anterior hippocampus that are not yet measurable in a MRI.

The ‘Knowledge’, as it is known, provides a lovely real-world example of expertise. Unlike most other examples of expertise development (e.g. music, chess), it is largely unaffected by childhood experience (there may be some London taxi drivers who began deliberately working on their knowledge of London streets in childhood, but it is surely not common!); it is developed through a training program over a limited time period common to all participants; and its participants are of average IQ and education (average school-leaving age was around 16.7 years for all groups; average verbal IQ was around or just below 100).

So what underlies this development of the posterior hippocampus? If the qualified and non-qualified trainees were comparable in education and IQ, what determined whether a trainee would ‘build up’ his hippocampus and pass the exams? The obvious answer is hard work / dedication, and this is borne out by the fact that, although the two groups were similar in the length of their training period, those who qualified spent significantly more time training every week (an average of 34.5 hours a week vs 16.7 hours). Those who qualified also attended far more tests (an average of 15.6 vs 2.6).

While neurogenesis is probably involved in this growth within the posterior hippocampus, it is also possible that growth reflects increases in the number of connections, or in the number of glia. Most probably (I think), all are involved.

There are two important points to take away from this study. One is its clear demonstration that training can produce measurable changes in a brain region. The other is the indication that this development may come at the expense of other regions (and functions).

IQ has long been considered to be a fixed attribute, stable across our lifetimes. But in recent years, this assumption has come under fire, with evidence of the positive and negative effects education and experiences can have on people’s performance. Now a new (small) study provides a more direct challenge.

In 2004, 33 adolescents (aged 12-16) took IQ tests and had their brains scanned. These tests were repeated four years later. The teenagers varied considerably in their levels of ability (77-135 in 2004; 87-143 in 2008). While the average IQ score remained the same (112; 113), there were significant changes in the two IQ scores for some individuals, with some participants gaining as much as 21 points, and others falling as much as 18 points. Clear change in IQ occurred for a third of the participants, and there was no obvious connection to specific attributes (e.g., low performers didn’t get better while high performers got worse).

These changes in performance correlated with structural changes in the brain. An increase in verbal IQ score correlated with an increase in the density of grey matter in an area of the left motor cortex of the brain that is activated when articulating speech. An increase in non-verbal IQ score correlated with an increase in the density of grey matter in the anterior cerebellum, which is associated with movements of the hand. Changes in verbal IQ and changes in non-verbal IQ were independent.

While I’d really like to see this study repeated with a much larger sample, the findings are entirely consistent with research showing increases in grey matter density in specific brain regions subsequent to specific training. The novel part of this is the correlation with such large changes in IQ.

The findings add to growing evidence that teachers shouldn’t be locked into beliefs about a student’s future academic success on the basis of past performance.

Postscript: I should perhaps clarify that IQ performance at each of these time points was age-normed - this is not a case of children just becoming 'smarter with age'.

Shrinking of the frontal lobe has been associated with age-related cognitive decline for some time. But other brain regions support the work of the frontal lobe. One in particular is the cerebellum. A study involving 228 participants in the Aberdeen Longitudinal Study of Cognitive Ageing (mean age 68.7) has revealed that there is a significant relationship between grey matter volume in the cerebellum and general intelligence in men, but not women.

Additionally, a number of other brain regions showed an association between gray matter and intelligence, in particular Brodmann Area 47, the anterior cingulate, and the superior temporal gyrus. Atrophy in the anterior cingulate has been implicated as an early marker of Alzheimer’s, as has the superior temporal gyrus.

The gender difference was not completely unexpected — previous research has indicated that the cerebellum shrinks proportionally more with age in men than women. More surprising was the fact that there was no significant association between white memory volume and general intelligence. This contrasts with the finding of a study involving older adults aged 79-80. It is speculated that this association may not develop until greater brain atrophy has occurred.

It is also interesting that the study found no significant relationship between frontal lobe volume and general intelligence — although the effect of cerebellar volume is assumed to occur via its role in supporting the frontal lobe.

The cerebellum is thought to play a vital role in three relevant areas: speed of information processing; variability of information processing; development of automaticity through practice.

The issue of “mommy brain” is a complex one. Inconsistent research results make it clear that there is no simple answer to the question of whether or not pregnancy and infant care change women’s brains. But a new study adds to the picture.

Brain scans of 19 women two to four weeks and three to four months after they gave birth showed that grey matter volume increased by a small but significant amount in the midbrain (amygdala, substantia nigra, hypothalamus), prefrontal cortex, and parietal lobe. These areas are involved in motivation and reward, emotion regulation, planning, and sensory perception.

Mothers who were most enthusiastic about their babies were significantly more likely to show this increase in the midbrain regions. The authors speculated that the “maternal instinct” might be less of an instinctive response and more of a result of active brain building. Interestingly, while the brain’s reward regions don’t usually change as a result of learning, one experience that does have this effect is that of addiction.

While the reasons may have to do with genes, personality traits, infant behavior, or present circumstances, previous research has found that mothers who had more nurturing in their childhood had more grey matter in those brain regions involved in empathy and reading faces, which also correlated with the degree of activation in those regions when their baby cried.

A larger study is of course needed to confirm these findings.

A small study comparing 18 obese adolescents with type 2 diabetes and equally obese adolescents without diabetes or pre-diabetes has found that those with diabetes had significantly impaired cognitive performance, as well as clear abnormalities in the integrity of their white matter (specifically, reduced white matter volume, especially in the frontal lobe, as well as impaired integrity in both white and grey matter). Similar abnormalities have previously been found in adults with type 2 diabetes, but the subjects were elderly and, after many years of diabetes, generally had significant vascular disease. One study involving middle-aged diabetics found a reduction in the volume of the hippocampus, which was directly associated with poor glycaemic control.

It remains to be seen whether such changes can be reversed by exercise and diet interventions. While those with diabetes performed worse in all cognitive tasks tested, the differences were only significant for intellectual functioning, verbal memory and psychomotor efficiency.

A study comparing the brains 32 adult women with Anorexia Nervosa and 21 healthy women has revealed that when the women with anorexia were in a state of starvation they had less brain tissue (especially in grey matter) compared to the healthy women. Those who had the illness the longest had the greatest reductions in brain volume when underweight. Happily, these deficits began to reverse after several weeks of weight gain.

[1588] Roberto, C. A., Mayer L. E. S., Brickman A. M., Barnes A., Muraskin J., Yeung L-K., et al.
(2010).  Brain tissue volume changes following weight gain in adults with anorexia nervosa.
International Journal of Eating Disorders. 9999(9999), NA - NA.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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."

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.

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.

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.

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.

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.,4273,4108165,00.html