Failure to remap visuotactile space across the midline in the split-brain

We examined the effect of posture change on the representation of visuotact ile space in a split-brain patient using a cross-modal congruency task. Spl it-brain patient J.W. made speeded elevation discrimination responses (up v ersus down) to a series of tactile targets presented to the index finger or thumb of his right hand. We report congruency effects elicited by irreleva nt visual distracters placed either close to, or Far from, the stimulated h and. These cross-modal congruency effects followed the right hand as it mov ed within the right hemispace, but failed to do so when the hand crossed th e midline into left hemispace. These results support recent claims that int erhemispheric connections are required to maintain an accurate representati on of visuotactile space.