Eureka! fMRI discovers brain region responsible for insight
Many people have ?light bulb? moments. After they?ve been stymied by a problem, the solution suddenly hits them with a flash. This flash of insight is a real biological phenomenon, according to a study published online in the April Public Library of Science Biology.
Mark Jung-Beeman, Ph.D., and Edward M. Bowden, Ph.D., of Northwestern University, John Kounios, Ph.D., of Drexel University, and colleagues at Source Signal Imaging in San Diego used fMRI and EEG to map out neural activity during problem solving in 13 and 19 subjects, respectively.
Problems were constructed to evoke insight about half the time. Whenever subjects solved the problem, they pressed a button indicating whether they used insight. Before being given the problems, they were told that an insight moment is a kind of ?Aha!? characterized by suddenness and obviousness after the fact.
The researchers observed two objective neural correlates of insight. Insight relative to noninsight solutions sparked increased activity in the right hemisphere anterior superior temporal gyrus revealed on fMRI.
EEG recordings revealed a sudden burst of high-frequency (gamma-band) neural activity in the same area beginning 0.3 seconds prior to insight solutions. Since EEG does not have the spatial resolution of fMRI, researchers used the Laplacian transform to localize observed activity.
?In the right hemisphere, the anterior superior temporal gyrus helps pull together distantly related information that might otherwise be missed,? said Jung-Beeman, an associate professor of psychology at Northwestern. ?This sometimes helps people derive an implicit theme or gist of a story, understand metaphors, or draw connective inferences.?
Researchers are confident that the gamma burst in the right temporal area is not related to motor processes involved in making the response for several reasons: · Motor activity associated with the bimanual button press would have caused a bilateral gamma burst, not a unilateral one. · The location of the gamma burst as determined by Laplacian mapping is not consistent with hand-related motor cortex activity. · Both insight and noninsight solutions required button presses.
The authors write that complex problem solving requires a complex cortical network to encode the problem information, search memory for relevant information, and evaluate the information. Their experiment demonstrates that solving verbal problems with insight requires at least one additional component: the right hemisphere anterior superior temporal gyrus, which is less important to problem solving without insight.
The right anterior temporal area is associated with making connections across distantly related information during comprehension. Although all problem solving relies on a largely shared cortical network, the sudden flash of insight occurs when solvers engage distinct neural and cognitive processes that allow them to see connections that had previously eluded them.
Patients with damage in the right anterior temporal area may have difficulty filling in the gaps between distantly related chunks of information unless someone points out their relationships, Jung-Beeman said. These patients might have to make a special effort to assemble the big picture.
Jung-Beeman and colleagues are studying other types of insight including suddenly ?seeing? an object in a degraded visual picture or switching between interpretations of an ambiguous picture.
?We predict that we will see similar patterns of brain activity, and that the right hemisphere anterior inferior temporal lobe will be critical to this insight,? he said.
For more information from the online Diagnostic Imaging archives: