The Neuroscience of Gender
Co-Sponsor: RWTH Aachen University
Gender differences in the brain and in behavior are influenced by sex hormones and gender stereotypes. Ute Habel, professor of neuropsychological gender research at RWTH Aachen University, and Bruce McEwen, professor and head of the Laboratory of Neuroendocrinology at Rockefeller University, discussed the possible implications of these structural and functional influencing factors. Anke A. Ehrhardt, professor of medical psychology at Columbia University Medical Center, moderated the discussion.
According to McEwen, the entire brain is a target of sex and stress hormones. Sex hormones affect many regions and functions of the brain including memory, motor coordination, pain sensitivity, and mood. They also display neuroprotective effects that can reduce negative neuronal consequences of Parkinson’s or Alzheimer’s. Suppressing sex hormone production through hormone therapy can have negative results and lead, among other consequences, to an increased risk of stroke, as well as mood dysregulations, which can possibly result in a full-blown depression. “There are potential trade-offs in the use of these pharmacologic agents,” said McEwen, “biologists and patients have to be aware of them and their potential dangers.”
Other structural gender differences of the brain, for instance, how male and female brains respond to stress are also dependent on the presence of estrogen and testosterone. While stress in male brains causes dendrites to shrink, the opposite happens in female brains where, due to the presence of estrogens and an increased neuronal communication with the amygdala, the same stress causes dendrites to expand. Consequently, sex hormones lead to gender-specific strategies when dealing with social and physical environments.
Habel, whose research focuses on neuropsychological factors of gender differences in healthy and psychiatric patients, addressed possible functional gender differences in the brain. According to her, men and women often display the same emotional and behavioral reactions, despite demonstrating clear differences in cerebral activity. One possible interpretation of this fact, said Habel, is that men and women use different processing strategies to reach the same conclusion.
Further functional contributions to gender differences in cognitive abilities are sociologically-induced gender stereotypes. “Stereotypes have an extremely powerful influence on brain and behavior,” said Habel. Suggesting that one gender is better at performing a task than the other can influence the subject’s performance. For this reason, conforming to a certain negative gender stereotype often results in a dramatic drop of the performance. This effect can be observed, in particular, in women.
“We suspect that there are many other sex differences in the brain that remain to be discovered,” said McEwen. The bottom line is that males and females do many of the same things equally well, but use different strategies to reach these points. Although the end point is the same, the consequences for the individual can vary significantly. One example is the gender-specific reactions during stress, which lead to an increased level of anxiety in women, in contrast to a higher substance abuse and antisocial behavior in men.