Linking sex and hemisphere in cognitive strategies

Sex differences in cognitive tasks are attributed to the use of different cognitive strategies. Especially in spatial tasks, these strategies share the common principle that men are oriented towards more global stimulus aspects, while women are oriented towards more local stimulus aspects/details. There is some evidence for a similar dissociation in verbal tasks. As demonstrated in project J3165- G17 there are indeed sex differences in global-local processing per se, which are in addition heavily dependent on the female menstrual cycle. Since hemispheric asymmetries between globally and locally directed attention are well documented, it is plausible that mechanisms of inter-hemispheric communication (in particular inhibition) play an important role in global-local processing. It has been demonstrated that inter-hemispheric inhibition and hemispheric asymmetries during spatial and verbal tasks are hormone dependent. While estrogen facilitates inter-hemispheric inhibition, progesterone reduces inter-hemispheric inhibition. Thus, hemispheric asymmetries are strongest during the late follicular phase right before ovulation and weakest during the mid-luteal phase about a week following ovulation. In line with this observation, reaction time effects during global- local processing are reduced during the mid-luteal cycle phase (J3165-G17). Therefore, we assume that estrogen and progesterone dependent modulation of inter-hemispheric communication explains sex differences in the selection of global and local stimulus aspects and is the substrate for sex specific cognitive strategies. This project aims to investigate inter-hemispheric interactions during global-local processing in relation to estrogen and progesterone levels using EEG and fMRI methodology and to relate these findings to sex differences in spatial and verbal tasks.