The effects of subcortical sensory and motor lesions on conditioned tactile placing in cats with pyramid section.

ABSTRACT

Cats after unilateral bulbar pyramid section showed permanent loss of tactile placing in the contralateral limbs. However, the cats could be trained to place the forelimb following light touch in a conditioning situation with food as a reward. This conditioned response survived subsequent unilateral red nucleus and cerebellar interposed nucleus lesions. Dorsal quadrant spinal cord lesion at the cervical level produced initial loss of the conditioned tactile placing but is recovered without retraining. Since those lesions interrupted subcortical afferent and efferent pathways essential to reflex tactile placing, these results indicate that reflex and conditioned responses involve different pathways and mechanisms. Training recruits or activates additional pathways for conditioned responses rather than strengthening those subserving the reflex responses.