INTERHEMISPHERIC-TRANSFER TIME AND CORPUS-CALLOSUM SIZE

WE examined the relationship between the size of five midsagittal corp us callosum subareas (measured with in vivo magnetic resonance morphom etry) and hand reaction times at dichotic consonant-vowel monitoring i n fifty healthy young adults. Based on the reaction times, interhemisp heric transfer times between auditory and motor brain areas were calcu lated and related to anterior and posterior corpus callosum subarea me asurements. We found no relationship between the size of callosal suba reas and auditory or motor interhemispheric transfer times. We did, ho wever, find a significant correlation between mean reaction time and t otal corpus callosum size. Our results suggest that normal variation i n callosal size or shape is not related to individual differences in a uditory lateralization. Instead, callosal size may be associated with speed of information processing.