Projections to the cat's cerebral cortex from low threshold joint afferents.

Abstract

AbstractThe projections to the cerebral cortex from the contralateral low threshold afferents of the musculocutaneous branch to the elbow joint (Ejt) and the posterior knee joint nerve (Kjt) were investigated in cats anesthetized with chloralose. Graded electrical stimulation of the nerves was used to evoke the cortical potentials. Three discrete joint projection areas were found in the cytoarchitectonic area 3 of the posterior sigmoid gyrus, i.e. one Ejt and two Kjt loci. These loci overlapped with the projections from group I muscle afferents. One Ejt and one or two Kjt loci were observed in positions corresponding to cytoarchitectonic areas 1 and 2. They did not receive input from group I muscle afferents. A separate locus with overlap between forelimb joint and muscle afferents was located in area 4 y. Components 1 and II of the joint nerve volley evoked short latency potentials in all cortical loci. Low threshold cutaneous afferents evoked responses in all joint loci. The spinal course of the ascending Ejt path was mainly located in the dorsal column. Kjt component I afferents travelled mainly in the dorsal columns and component I and II afferents in the dorsolateral fascicle. The Kjt path in the dorsolateral fascicle ascended uncrossed to the level of Ci.