AFFERENT RELATIONS OF INFERIOR OLIVARY NUCLEUS: III. ELECTROPHYSIOLOGICAL DEMONSTRATION OF A SECOND RELAY IN DORSAL SPINO-OLIVARY PATHWAY IN CAT

Abstract

The dorsal spino-olivary pathway is distinct from that of the dorsal spino-cerebellar tract, since stimulation of the latter at the restiform body does not cause olivary activity, nor does stimulation of the olive elicit responses at the spino-cerebellar site. Only small antidromic surface activity, confined to the uppermost cervical segments of the cord results from stimulating the contralateral olive. This indicates that a relay must exist between the secondary, dorsal spino-olivary tract and its final termination, as a tertiary system, at the contralateral olive. The site of relay was indicated as in the dorsal quadrant of the uppermost cervical segments on the side of the ascending spinal tract. The decussation of the tertiary relayed pathway occurs in the region between the second cervical segment and slightly above the obex.