Trigeminal and olfactory synergism in the perception of smell.

In normal subjects olfactory evoked cortical potentials are seen with latencies of 150 m/sec and 350 m/sec. To evaluate the site of potential generators in central nervous pathways olfactory evoked cortical potentials were registered in patients with well-defined lesions of the central nervous system and the maxillary nerve. Absence of the first potential was seen in lesions of the brain-stem and the maxillary nerve. Absence of the second potential was observed in lesions of the frontal cerebral medulla and the temporal cortex. No olfactory potentials were found in circumscribed lesions of the postcentral cortex. Sites of the lesions were controlled by computed tomography. Appearance of the two potentials is correlated to normal perception of smell which is established by combined olfactory and trigeminal nerve function.