Characteristics of Corticocortical Ipsilateral Connections of the Primary, Secondary, and Tertiary Sensorimotor Zones of the Cat Cerebral Cortex

Abstract

Experiments on 30 cats using the Nauta–Gigax method addressed the comparative distribution of associative fibers in the primary motor MI (field 4y) and the secondary SMII (2pri) and tertiary SMIII (field 5) sensorimotor zones of the cortex. A minor proportion of associative fibers was found to project to the primary sensory zone SI (fields 1, 2, 3a, 3b). Massive bilateral connections between the MI and the SMII (2pri) and SMIII (field 5) were demonstrated. It is suggested that recovery of motor functions after local lesions to SMI, SMII, and SMIII occur as a result of these multiple horizontal associative connections between the functional circuits of these sensorimotor centers.