Instrumental learning within the spinal cord: I. Behavioral properties

Four experiments are reported that explore whether spinal neurons can support instrumental learning. During training, one group of spinal rats (master) received legshock whenever one hindlimb was extended. Another group (yoked) received legshock independent of leg position. Master, but not yoked, rats learned to maintain their leg in a flexed position, exhibiting progressively longer flexions as a function of training (Experiment 1). All subjects were then tested by applying controllable shock to the same leg (Experiment 2). Master rats reacquired the instrumental response more rapidly (positive transfer), whereas yoked rats failed to learn (a learned helplessness-like effect). Disrupting response-outcome contiguity by delaying the onset and offset of shock by 100 ms eliminated learning (Experiment 3). Experiment 4 showed that shock onset contributes more to learning than does shock offset.