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News reports of research into memory August 2001

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August 2001

Evidence from a series of studies using functional positron emission tomography (PET) images suggests that one way older adults may compensate for age-related cognitive decline is by using additional regions of the brain to perform memory and information processing tasks. For example, simple short-term memory tasks involve the same brain regions in both older and younger adults, but older adults also activate a frontal cortex region that young adults use only when performing complex short-term memory tasks. This may explain why performance of older adults on complex memory tasks is usually significantly poorer than that of younger adults - the frontal cortex region that young adults will activate to help with complex short-term memory tasks is already preoccupied in older adults, and is less available to help when the task becomes more complex.
The research was conducted by University of Michigan researchers under the leadership of cognitive neuroscientist Patricia Reuter-Lorenz.
It was presented at the annual meeting of the American Psychological Association in San Francisco
http://www.umich.edu/~newsinfo/Releases/2001/Aug01/r081501a.html
http://news.bmn.com/news/story?day=010827&story=2

Carnegie Mellon scientists using magnetic resonance imaging found quite different brain activity patterns for reading and listening to identical sentences. During reading, the right hemisphere was not as active as expected, suggesting a difference in the nature of comprehension experienced when reading versus listening. When listening, there was greater activation in a part of Broca's area associated with verbal working memory, suggesting that there is more semantic processing and working memory storage in listening comprehension than in reading. This should not be taken as evidence that comprehension is better in one or other of these situations, merely that it is different. "Listening to an audio book leaves a different set of memories than reading does. A newscast heard on the radio is processed differently from the same words read in a newspaper."
Carnegie Mellon Psychology Professor Marcel Just of the Center for Cognitive Brain Imaging at Carnegie Mellon (www.ccbi.cmu.edu) co-authored the report that appears in this month's issue of the journal Human Brain Mapping.
http://www.eurekalert.org/pub_releases/2001-08/cmu-tma081401.php

While practicing several different skills in separate, concentrated blocks leads to better performance during practice, it appears that this approach is not the best method of learning for long-term retention. The temporary improvement in performance that results from blocked practice hinders learning because it allows people to overestimate how well they have learned a skill. For long-term retention, it appears that contextual-interference practice (practicing skills that are mixed with other tasks) results in better learning. This may be because such practice requires people to repeatedly retrieve the motor program corresponding to each task (repeated retrieval is a major factor in making stored memories easier to access). Such practice also requires the person to differentiate the skills in terms of their similarities and differences, which may be assumed to result in a better mental conceptualization of those skills. The fact that blocked practice leads to better short-term performance but poorer long-term learning "has great potential to fool teachers, trainers and instructors as well as students and trainees themselves."
The research was reportd in the Journal of Experimental Psychology: Learning, Memory and Cognition. Full reference
http://www.apa.org/releases/retention.html

Studies of more than 350 men and women between the ages of 20 and 90 have found that cognitive decline starts as early as the twenties, and this decline in cognitive processing power appears to be constant - that is, the rate of decline is the same when you are in your twenties as when you are in your sixties. However young adults don't notice this decline because the loss hasn't yet become great enough to affect everyday activities.
Denise Park, who directs the Center for Aging and Cognition at the University of Michigan Institute for Social Research (ISR) presented a paper on these studies on Aug. 24 in San Francisco at the annual meeting of the American Psychological Association.
http://www.umich.edu/~newsinfo/Releases/2001/Aug01/r081301a.html

A magnetic-resonance study has found that professional musicians use their left brain more than other people when listening to music. In particular, while the planum temporale was activated in all subjects listening to music (a Bach piece), in non-musicians it was the right planum temporale that was most active, while in musicians the left side dominated. The left planum temporale is thought to control language processing. It may be that musicians process music as a language.This left-hand brain activity was most pronounced in people who had started musical training at an early age, as well as in those with absolute or 'perfect' pitch (suggesting that musical traits such as absolute pitch are the result of childhood training rather than genetic predisposition).
The study was reported in volume 11 of Cerebral Cortex. Full reference
http://www.nature.com/nsu/010816/010816-4.html

Professor Thomas Elbert, Ognjen Amidzic and colleagues at the University of Constance, Germany, used a new magnetic imaging technique to study chess players' brains in action. They found that mid-match activity in grandmasters' brains is mainly in regions thought to be involved in long-term memory - the frontal and parietal cortices. Amateur chess players relied more on the medial temporal lobe, which helps to encode new information, suggesting that they analyse situations afresh. The finding supports the idea that expertise depends on stored memory chunks that are called up when needed.
The report appeared in Nature, 412, p603. Full reference
http://www.nature.com/nsu/010809/010809-13.html
http://news.bbc.co.uk/hi/english/sci/tech/newsid_1480000/1480365.stm

Confirmation of what many of us know, and many more try to deny - you can't do two complex tasks simultaneously as well as you could do either one alone. Previous research has showed that when a single area of the brain, like the visual cortex, has to do two things at once, like tracking two objects, there is less brain activation than occurs when it watches one thing at a time. This new study sought to find out whether something similar happened when two highly independent tasks, carried out in very different parts of the brain, were done concurrently. The two tasks used were language comprehension (carried out in the temporal lobe), and mental rotation (carried out in the parietal lobe). The language task alone activated 37 voxels of brain tissue. The mental rotation task alone also activated 37 voxels. But when both tasks were done at the same time, only 42 voxels were activated, rather than the sum of the two (74). While overall accuracy did not suffer, each task took longer to perform.
The study, published in the Aug.1 issue of the journal NeuroImage, was led by Dr. Marcel Just, co- director of the Center for Cognitive Brain Imaging at Carnegie Mellon University in Pittsburgh.
http://www.nytimes.com/2001/07/31/health/anatomy/31BRAI.html?ex=997618712&ei=1&en=21bbb84d9332faf3

Technology increasingly tempts people to do more than one thing (and increasingly, more than one complicated thing) at a time.New scientific studies reveal the hidden costs of multitasking. In a study that looked at the amounts of time lost when people switched repeatedly between two tasks of varying complexity and familiarity, it was found that for all types of tasks, subjects lost time when they had to switch from one task to another, and time costs increased with the complexity of the tasks, so it took significantly longer to switch between more complex tasks. Time costs also were greater when subjects switched to tasks that were relatively unfamiliar. They got "up to speed" faster when they switched to tasks they knew better. These results suggest that executive control involves two distinct, complementary stages: goal shifting ("I want to do this now instead of that") and rule activation ("I'm turning off the rules for that and turning on the rules for this").
The study was published in Journal of Experimental Psychology: Human Perception and Performance. Full reference
http://www.apa.org/journals/xhp/press_releases/august_2001/xhp274763.html

Claus Hilgetag, of Boston University, and his colleagues fired focused magnetic pulses through healthy subjects' skulls for 10 minutes to induce 'hemispatial neglect'. This condition, involving damage to one side of the brain, leaves patients unaware of objects in the opposite half of their visual field (which sends messages to the damaged half of the brain). The subjects showed the traditional symptoms of hemispatial neglect. They were worse at detecting objects opposite to the numb side of their brain, and worse still if there was also an object in the functioning half of the visual field. Yet numbed subjects were better at spotting objects with the unaffected half of their brains. This behaviour confirms the idea that activity in one half of the brain usually eclipses that in the opposite half. The finding supports the idea that mental activity is a tussle between the brain's many different areas.
The study was reported in Nature Neuroscience. Full reference
http://www.nature.com/nsu/010830/010830-5.html

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