A study led by the Rotman Research Institute at Baycrest Centre for Geriatric Care in Toronto has found that older people use different areas of the brain to perform the same 'thinking task' as young.
The study, in conjunction with University of Toronto and Brandeis University in Massachusetts, is published in the Oct. 25 international journal "Current Biology". While other studies have conducted comparisons of young and old brain activity, this is the first to focus on how the interplay of brain regions relates to cognitive functioning and aging.
"The older brain is more resilient than we think," says Dr. Randy McIntosh, Rotman scientist and assistant professor, Department of Psychology, at University of Toronto. "If aging brains can find ways to compensate for cognitive decline, this could have exciting implications for memory rehabilitation."
Ten young adults (ages 20 to 30) and nine older adults (ages 60 to 79) participated in identical visual, short-term memory tests while their brain activity was measured using positron emission tomography (PET). PET measures regional cerebral blood flow and acts as a marker to show which brain areas are 'lighting up' during a memory performance task.
Participants were shown pairs of vertical grid patterns on a computer screen and asked to select which one had the higher spatial frequency. After viewing each pair, they would press one of two keys to indicate the correct grid. Researchers measured their ability to discriminate stimuli over half-second and four-second intervals.
Results show that young and older participants perform the memory task equally well, but the neural systems or pathways supporting performance differed between young and old. While there was some overlap in the brain regions supporting performance (e.g. occipital, temporal and inferior prefrontal cortices), the neural communication among these common regions was much weaker in older individuals.
Older individuals compensated for this weakness by recruiting 'unique' areas of the brain, including hippocampus and dorsal prefrontal cortices. Scientists are most fascinated by the older brain's activation of the hippocampus because this area is generally used for more complicated memory tasks such as learning lines from a Shakespeare play.
Dr. McIntosh was assisted in the study by Dr. Allison Sekuler, Department of Psychology, University of Toronto, and her father Dr. Robert Sekuler at Brandeis University.
Funding for the study was provided by the Alzheimer's Assocation of America, the Natural Sciences and Engineering Research Council of Canada, and Medical Research Council of Canada.
A BRAIN DIAGRAM SHOWING 'UNIQUE' AREAS ACTIVATED IN OLDER BRAINS IS AVAILABLE UPON REQUEST.
Journal
Current Biology