The researchers said that, although their finding is basic, it raises the potential of using either training or drugs to enhance cognitive function in the elderly by increasing "recruitment" of the left prefrontal cortex.
The evidence for compensatory brain activity in the high-performing elderly was reported in the November 1, 2002, issue of NeuroImage, by a research team led by Roberto Cabeza of Duke's Center for Cognitive Neuroscience. Other co-authors are Nicole Anderson, Jill Locantore and Anthony McIntosh of the University of Toronto.
In their study, Cabeza and his colleagues sought to better understand a phenomenon seen in previous studies, in which older people tend to show a reduced "hemispheric asymmetry" in activity of the two sides of the prefrontal cortex with aging. The prefrontal cortex, the brain region just behind the forehead, is where higher-level cognitive processing takes place.
Past research has shown that in young people certain cognitive tasks are carried out by the right frontal cortex, but older people tend to lose that asymmetry of processing. They tend to show more bilateral activity of the two brain hemispheres during such tasks.
Neuroscientists have proposed two divergent theories to explain this change with age. According to the "dedifferentiation" theory, age-related reduction in asymmetry occurs because older adults become less able to recruit specialized neural mechanisms. In contrast, the "compensation" theory holds that the asymmetry reduction occurs largely because the elderly
Contact: Dennis Meredith