Control of digits via C3-C4 propriospinal neurones in cats; recovery after lesions.

C3-C4 propriospinal neurones (C3-C4 PNs) transmit the command for forelimb target-reaching in cats, while the command for food-taking is mediated by interneurones in the forelimb segments. The ability of the C3-C4 PNs to control digits has now been reinvestigated with combined lesions in dorsal C5 (transecting the cortico- and rubrospinal tracts) and ventral C2 (transecting reticulospinal tracts) leaving the C3-C4 PNs in sole control of the forelimb. Components of food-taking like flexion in the proximal interphalangeal joints were found in half of the cats. Supination and terminal flexion of the metacarpophalangeal joints by which normal cats bring the morsel of food to the mouth were lacking in all cats.