ANN ARBOR---A new analysis of the human brain at work, to be published in the March 12 issue of Science, elucidates how the frontal lobes are organized, providing strong evidence that verbal and spatial memories are processed in different hemispheres.
The analysis, by University of Michigan psychologists Edward E. Smith and John Jonides, focuses on working memory, a mental system that includes both the temporary storage of verbal, spatial and object information, and various "executive processes" for using that information. Among the processes are everyday mental activities such as paying attention to one source of information but not another as a way of dealing with conflicting information.
"How the frontal cortex is organized is a question of tremendous interest," says Smith, the Arthur W. Melton Collegiate Professor of Psychology and a research scientist at both the U-M Mental Health Research Institute and the U-M Institute for Social Research. "Our analysis suggests that it is partly organized by the type of information being processed, and partly by the type of operation being performed---either storage or active manipulation of the stored information."
Verbal storage tasks activate left-hemisphere speech areas, Smith and Jonides found, while spatial storage tasks activate specific areas of the right cortex, and storage of information about objects, such as smiling vs. frowning faces, activates still different, more ventral, or lower, regions at the front of the cortex.
Smith and Jonides also found that two of the fundamental executive processes---paying attention to one source of information rather than another, and switching from one task to another---activate specific regions at the front of the brain: the anterior cingulate and the dorsolateral prefrontal cortex.
Their analysis is based on brain imaging experiments, done at the U-M and
elsewhere, using PET (positron emission tomography) and functional MRI (magnetic
Contact: Diane Swanbrow
University of Michigan