An evoked potential study of different pathways from the hindlimb to the somatosensory areas in the cat.

Abstract

AbstractEvoked potentials from contralateral hindlimb nerves were recorded in SI and SII of cats anesthetized with Nembutal. Initially positive short latency potentials could be elicited from low threshold cutaneous afferents and low (groups I and II) and high (group III) threshold muscle afferents as well as high threshold afferents of the posterior knee‐joint nerve. The low threshold muscle afferents were not of stretch receptor origin. The effects were transmitted via two spinal pathways, the dorsal columns and the spinocervical tract. The transmission via the spinocervical tract was faster by 2 msec for cutaneous impulses and by 7 msec for impulses from group III muscle afferents. The finding of McIntyre (1962b) that the low threshold afferents of the interosseous nerve project mainly to SII via the dorsal columns was confirmed. After transection of the above‐mentioned pathways, initially negative short latency potentials could be elicited from low threshold cutaneous afferents and high threshold muscle afferents via a pathway in the ventral quadrant contralateral to the stimulated nerves.