Sex differences in the medial temporal lobe during encoding and recognition of pseudowords and abstract designs

Sex differences in various cognitive abilities have been demonstrated in terms of performance differentials and, more recently, in differences in activation patterns during fMRI. Hemispheric lateralization is sometimes accentuated in sex differences; e.g., women demonstrating greater activation of the left hemisphere than men during verbal tasks. We were interested in whether this phenomenon applies to memory for words and designs (i.e., material specific memory). Using analogous verbal (pseudowords) and nonverbal (abstract designs) encoding and recognition tasks completed back-to-back in a 3T scanner, we found that women tend to show exaggerated left hippocampal activation during certain stages of encoding and recognition of verbal information, compared with men. Likewise (although to a lesser extent), men showed more right hippocampal activation than women did during the abstract design learning task. These results have important implications for the generalization of fMRI memory study results, for example to clinical populations such as patients undergoing epilepsy surgery.