Classical conditioning of the flexion reflex in spinal cat: features of the reflex circuitry.

Classically conditioned facilitation of the flexor withdrawal reflex of spinal cat occurs in knee and ankle flexor muscles but not in a flexor muscle of the toes. Furthermore, the spinal circuitry activated by a component of the conditioned stimulus (A alpha cutaneous fibers) is not by itself involved in the reflex conditioning. The results suggest that increases in both cutaneous afferent output and motoneuron excitability may be eliminated as mechanisms contributing to conditioning and point to certain interneuronal pools as the locus of learning in this preparation.