Sex differences in brain regions activated by grammatical and reading tasks.

Do the brains of men and women show similar patterns of functional organization for language, or are men more strongly lateralized? We used PET to measure cerebral blood flow (CBF) as men and women read real and nonce verbs, and produced past tense forms. While the overall patterns of reaction time, error, and brain activation were similar, there were also significant sex-related differences in CBF patterns. During the past tense generation tasks, men showed left-lateralized activation while women recruited bilateral perisylvian cortex, confirming differences in functional laterality. During all tasks, women showed higher activation in occipital and/or cerebellar regions, suggesting differences in basic reading strategies. We conclude that sex differences in functional cortical organization exist in the absence of significant behavioral differences.