A key part of the brain involved in processing emotionally-influenced memories acts differently in men and women, even in the absence of stimuli, UC Irvine researchers have found.
Larry Cahill, an associate professor of neurobiology and behavior, and Lisa Kilpatrick, a former postdoctoral fellow in his laboratory, have found that the amygdala, an almond-shaped structure found on both sides of the brain, behaves very differently in males and females while the subjects are at rest. In men, the right amygdala is more active and shows more connections with other regions of the brain, even when there is no outside stimulus. Conversely, in women, the left amygdala is more connected with other regions of the brain. In addition, the regions of the brain with which the amygdala communicates while a subject is at rest are different in men and women.
The finding could be key to determining why gender-related differences exist in certain psychiatric disorders and how to treat a variety of illnesses.
"These findings are intriguing because they provide the first hint of what could be a fundamental difference in how the brain is wired in men and women," said Cahill, a fellow at UCI's Center for the Neurobiology of Learning and Memory. "If, even in a resting state, the brain shows such differences between the sexes, it could have far-reaching implications for our study of certain psychiatric and medical disorders."
The researchers used Positron Emission Tomography (PET) scans to analyze the brains of 72 healthy, right-handed adults (36 men and 36 women). The subjects were instructed to relax with their eyes closed while being scanned. When the scans were later studied, researchers found that not only was there a difference between the men and women as to which hemisphere's amygdala was more active, but also that the regions of the brain that the amygdala "talked" with were also quite different. In men, the right-hemisphere amygdala showed more connectivity with brain regions such as the visual cortex and the striatum. In contrast, the left amygdala in women was more connected to regions such as the insular cortex and the hypothalamus.