X-Message-Number: 12692
Date: Mon, 01 Nov 1999 18:18:49 -0500
From: Jan Coetzee <>
Subject: brain not hardwired

Brain re-wiring appears likely

 By Penny Stern, MD

 NEW YORK, Nov 01 (Reuters Health) -- The aging brain appears to
 be able to reconfigure its circuitry in order to compensate for
 age-related deficits, a multinational research group reports in the
 November issue of the journal Current Biology.

 Lead author Dr. A.R. McIntosh of the Rotman Research Institute of
 Baycrest Centre and the University of Toronto in Canada, explained to
 Reuters Health how his team reached its conclusions. ``We used a
 very simple visual memory task to test what brain circuits supported
 memory performance. This task was chosen because there is no age
 difference in performance,'' he said.

 What does differ, McIntosh continued, is the specific brain circuitry
 engaged to complete the memory task. ``There are a collection of
 regions near the back and sides of the brain -- (the) occipital and
 temporal cortex -- that form a strong circuit in young (study)
 he noted. In contrast, older brains use other brain areas such as the
 hippocampus and the dorsal prefrontal cortex, which are usually
 associated with more complex memory operations, like learning lines
 of a play or navigating around a new place, according to McIntosh.

 ``It is possible,'' he suggested, ``that the changes in more complex
 memory in the elderly reflect the fact that (these areas) are recruited
 support more simple memory functions and are (therefore) not
 available to carry out the more demanding complex memory

 The study findings may turn a long-held belief on its ear, however,
 since conventional wisdom holds that ``once you are over about 18
 years old, your brain is hardwired and if you lose something through
 damage, disease or normal deterioration, you are left with a 'hole' and

 that's it,'' McIntosh told Reuters Health. ``What we are seeing is that

 these brain circuits are not static and can change their... operation
 throughout life.''

 The practical implications of these results may include ''(using) the
 information about how the brain adapts to change to evaluate rehab
 strategies and perhaps suggest new avenues to pursue,'' McIntosh said.
 He added that this type of research ''is ongoing at the Rotman Research

 Institute... through a large international collaboration focusing on
 cognitive rehabilitation.'' Cognition encompasses brain processes
 involving thinking, learning, and memory.

 Before these still early findings can be applied to any current rehab
 regimens, McIntosh explained that his group's next step ``is to see
 when the changes in the brain circuits start... (which) means measuring

 brain-behavior relationships across several points in the lifespan:
 from children to young adults to middle-aged to old and very old
 individuals.'' He concedes that this type of research can be
 ``extraordinarily time-consuming'' and that it may be ``five years
 before we get any reasonable results.''

 Nevertheless, McIntosh believes that while ``people should not come
 away with the impression that the brain has an unlimited or untapped
 capacity... a cautious optimism about the resiliency of the brain is
 warranted at present.'' He concludes that ``within some boundaries,
 there may be room for quite a bit of change in the brain.''

 SOURCE: Current Biology 1999;9:1275-1278.

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