Sex but no hand difference in the isthmus of the corpus callosum.

We performed high-resolution magnetic resonance morphometry of the total midsagittal area and seven midsagittal subareas of the corpus callosum in healthy young adult dextrals and sinistrals (N = 52). There was no influence of handedness on these anatomic measurements. However, an effect of sex emerged, with women (N = 26) having a larger proportional isthmus segment of the callosum. This may reflect a sex-specific difference in the interhemispheric connectivity and functional organization of the temporoparietal association cortex.