Topography of C1 nerve- and trigeminal-evoked potentials in the ventrobasal complex of the cat thalamus.

In order to provide information pertaining to the C1 nerve representation in the thalamus, C1 nerve- and trigeminal-evoked potentials were recorded throughout the ventrobasal complex of the cat thalamus. Contralateral electrical stimulation of the C1 nerve and maxillary division of the trigeminal nerve elicited multiphasic positive-to-negative responses with mean maximum positive peak latencies of 2.2 ms and 2.7 ms, respectively. Ipsilateral stimulation failed to elicit a thalamic response. Construction of isopotential contour maps revealed that the foci of activity elicited by contralateral C1 nerve and trigeminal stimulation were located in the dorsolateral and ventromedial sections of ventroposterior medial nucleus (VPM), respectively.