LATERALIZATION OF OLFACTORY PERCEPTION IN SURGICALLY SEPARATED HEMISPHERES OF MAN

Five right-handed human subjects in whom the cerebral hemispheres had been surgically deconnected for alleviation of severe epileptic seizures were examined for lateralization of olfaction. As with vision and stereognosis, it was found that olfactory perception may be confined to a single hemisphere when the input is restricted to one side (i.e. to a single nostril). The fact that odors were recognized only in the hemisphere ipsilateral to the nostril stimulated was evidenced by the subject's ability to name odors from the left but not from the right nostril. Non-verbal tests demonstrated perceptual recognition of the right nostril odors in the non-speaking (right) hemisphere. The results were further substantiated in tasks that involved cross-modal olfacto-tactual matchings. Responses were successful when both the tactual and olfactory stimuli projected to the same hemisphere but not if they projected to opposite hemisphere. © 1969.