onverbal information.
Using functional magnetic resonance imaging (fMRI), Kelley and colleagues performed two experiments. In the first, they imaged five subjects who were asked to memorize written words, line drawings of objects such as frogs and ladders, and pictures of faces they would be unable to name. Subsequent testing showed they remembered these words, namable objects and unfamiliar faces very well, though they did best with namable objects.
In a second experiment, five different subjects were asked to memorize the test images. At a later time, they were asked to just look at them.
All of the subjects activated a region in the upper part of the left frontal lobe when they were memorizing words. If you put your finger on top of your head, and move it to the front between your left ear and your hair's midline, you will be near that region. The region activated by the unfamiliar faces was in a corresponding position on the right side of the brain. "This is the most clear-cut finding I've ever seen in an imaging study," Petersen says.
"The main conclusion from this study is that regions in the frontal lobe can be affected by the type of material you are trying to memorize," Kelley says. "But an interesting tidbit is that performance was best with namable objects, which activated both sides of the brain. So in a sense, two sides are better than one. If you use both sides, you're more likely to remember an object later."
The second experiment showed that the frontal lobes are affected by instructions that people receive. These brain regions become much more active when people are told to memorize information than when they are told to just look.
While this study focused on the normal brain, Petersen speculates that the results might be useful to patients with stroke or head injury. "If you get a lesion in the left frontal lobe, you might be better off developing a nonverbal strategy for remembering things," he says. "If the lesion is on the right, you might want to try a verbal strategy."
Kelley WM, Miezin FM, McDermott KB, Buckner RL, Raichle ME, Cohen NJ, Ollinger JM, Akbudak E, Conturo TE, Snyder AZ, Petersen SE. Hemispheric specialization in human dorsal frontal cortex and medial temporal lobe for verbal and nonverbal memory encoding. Neuron 20, 927-936, May 22, 1998.
Grants from the National Institutes of Health, the Charles A. Dana Foundation and the McDonnell Center for Higher Brain Function supported this research.
The above post is reprinted from materials provided by Washington University School Of Medicine. Note: Materials may be edited for content and length.
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