Sharing Information Between the Brain’s Hemispheres

Psychologist Explores How Age Affects How the Mind Processes Information

August 6, 2007

By Pam McLaren

A participant in a research study looks at a fixation cross in the center of a computer screen and sees the letters “A” and “B” on either side of the screen. The participant is then asked to match one of the letters to a third letter located below the others but on one side or other of the fixation cross: another “A.” Studies have shown that the processing of such information usually produces awithin-hemisphere, or one side of the brain, advantage.

Then the participant is asked to match the letters “A” and “B” to a third letter, this time a lower case “b.”  Not quite as simple as the first test, this time the information usually produces an across-hemisphere advantage.    

Young people typically process the upper and lower case information across both hemispheres but in older people, that’s not always the case, says Barbara Cherry, assistant professor of psychology. The difference prompted her to delve further into how seniors process information by conducting research with volunteers from the Osher Lifelong Learning Institute (OLLI) on campus.

“Few studies have looked at older adults,” when it comes to how the brain processes information with this type of behavioral task, Cherry says. “There have been discussions of degeneration in the white matter, or corpus callosum, in the brain. Both hemispheres are interconnected by the corpus callosum, and we know that both gray and white matter does change with age,” she notes.

Using healthy older adults without signs of stroke, dementia or depression, Cherry ran tests just as described above. The goal, she says, is to find out if the process changes due to simple aging.

“We wanted to find out how well the brain copes or compensates as it ages,” she said. “In our first study we found that older adults were less likely than younger adults to spread processing across both hemispheres for the name identity task, matching a to A.”

Earlier this year, Cherry expanded her research to study how college students vs. seniors appear to process information when it is digits — 1, 2, 3 — and dots, such as numbers as they are represented on a pair of dice.

With digits, young people have been found to process information within one side of their brain, and with dots, across the hemispheres, spreading the processing much like they do when matching upper- and lower-case letters. Do seniors process the information the same way?

“As the percentage of older adults grows in the United States, we face critical challenges both in terms of quality of life for aging adults and potential health care burdens,” says Cherry. “One way to address this is to better understand what happens to the brain and cognitive processing as we age to ultimately identify ways to preserve cognitive function, which may in turn extend independent functioning in older adults.”

Cherry, a CSUF alumna, has taught on campus since 2002. She holds a doctorate from USC, where she also has served as a postdoctoral fellow.