The anterior commissure in man: Functional variation in a multisensory system

The anterior commissure, which has been presumed to play a minor role in interhemispheric communication, was tested for the transfer of visual, auditory, and olfactory information in patients with complete sections of the corpus callosum. Four of five patients tested with presumed intact anterior commissures demonstrated interhemispheric transfer of verbal and pictorial stimuli presented visually to a single hemisphere. Evidence was also obtained for auditory and olfactory transfer, although successful interhemispheric communication in all three modalities was not found for any one patient. The data suggest that the human anterior commissure is capable of mediating multisensory, interhemispheric messages of a complex nature and provide evidence of functional plasticity in a phylogenetically early cerebral structure.