ASSOCIATIVE LEARNING OF AN ANTINOCICEPTIVE RESPONSE AT THE LEVEL OF THE SPINAL CORD IN INTACT RATS. P.A. Illich, K.D. Burks*, & J.W. Grau. Dept. of Psychology, Texas A&M Univ., College Station, TX 77843.
Prior work suggests that the circuitry needed to obtain conditioned antinociception exists at the level of the spinal cord. Because our past work used a reduced preparation (spinal) it is not clear whether this type of learning normally occurs in intact subjects. The present study addresses this issue by testing whether subjects that had been trained with the cord intact will exhibit conditioned antinociception after the cord has been transected. Twelve intact rats received differential conditioning (which controls for sensitization and pseudocontioning). One stimulus (the CS+) was paired with mild tail-shock (2-s, 0.5 mA), while the other (the CS-) was presented alone. Vibro-tactile stimuli to the left or right rear paw served as the CS+ and CS-. Which stimulus served as the CS+ was counterbalanced across subjects. The subjects received 30CS+ and 30 CS- trials spaced 1 min apart. One hr after training all subjects received a spinal transection at T@. Twentyfour hrs later pain reactivity during the CSs was tested with the tail-flick test. Ten of the twelve subjects exhibited longer tail-flick latencies during the CS+ relative to the CS- (p< .05). These results suggest spinal systems can support associative learning in intact subjects. Supported by BNS 881981 to J.W.G.
Published in Society for Neuroscience Abstracts, 17, 1991.