The application of neuroscience advances to brain injury is addressed in the context of our studies of the role of the corpus callosum in the interhemispheric transfer of auditory and tactile information. The outcome of these studies, which were conducted over a period of 30 years in normal individuals as well as those with congenital and acquired lesions of the corpus callosum, have since been confirmed and extended by modern brain imaging techniques. These techniques nevertheless continue to rely on the use of sensitive, specific, valid and reliable behavioural testing paradigms.

Interhemispheric interactions were studied with functional brain mapping of visual processing. Children performed a reaction time task with uni- and bilateral targets and nontargets. The visual evoked potential (VEP) was segmented into P1a, P1b, and N1 microstates using map rather than channel features. Map latencies, amplitudes and sources were tested for bilateral interactions. Bilateral targets yielded shorter VEP map latencies but later response onsets than unilateral ones. Source analyses of the unilateral VEPs indicated a transition from contra- (P1a) to ipsilateral (P1b) visual cortex activation (interhemispheric transfer). Bilateral VEPs were smaller than the summed unilateral VEPs in all microstates, indicating that interhemispheric interactions both precede and follow interhemispheric transfer. Brain mapping of uni- and bilateral VEPs in children thus revealed several distinct forms of interhemispheric interactions in the same, early time range.