Two hemispheres better than one for seniors.

• Position: Brain - Brief Article

Older adults use different regions of the brain than younger ones to perform the same memory and information processing tasks, according to University of Michigan, Ann Arbor, research. Conducted by cognitive neuroscientist Patricia Reuter-Lorenz and colleagues, it provides intriguing clues about how seniors compensate for some of the age-related declines in short-term memory and mental speed that tend to plague so many senior Americans. "Older adults activate both hemispheres of the brain to remember what younger adults can remember using just one hemisphere," she indicates.

When younger adults hold information in short-term memory, like rehearsing a phone number, they activate a network of brain regions involved in speech and short-term verbal storage. Older adults activate these areas as well, but show additional activation of a frontal cortex region that young adults use only when performing complex short-term memory tasks.

In one study, older and younger subjects were shown four letters, then asked to determine if a letter presented a few seconds later matched any of the initial four. As expected, Reuter-Lorenz found that seniors made more errors and were slower at the task than young subjects. PET scans of the subjects' brains while they were being tested showed that older subjects activated more areas of the brain in both hemispheres than young subjects, who showed activity mainly in the left hemisphere.

In another study of spatial memory, subjects were shown a group of marked locations on a screen, then presented a few seconds later with a single mark and asked to determine whether its position matched any in the earlier group. There again were different activation patterns for...