Atypical interhemispheric communication in left-handed individuals.

The relative latencies of evoked electroencephalogram potentials to lateralized visual stimuli were used to calculate the interhemispheric transfer time (IHTT) in right-handed and left-handed males. We confirmed earlier observations of a directional asymmetry in right-handed males. That is, IHTT from the right to the left hemisphere is significantly shorter than from the left to the right. We showed for the first time, however, that this directional asymmetry is not seen in left-handed males. It is suggested that differences in the cytoarchitechtonics of the right and left hemisphere (differences that may result in lateralization of function per se) underlie the asymmetric IHTT in right handers, and that these differences are less pronounced in left handers.