LATENT INHIBITION AND OVERSHADOWING OF A CONDITIONED ANTINOCICEPTIVE RESPONSE IN THE SPINALIZED RAT. J.A. Salinas, P.A. Illich and J.W. Grau. Dept. of Psychology, Texas A&M University, College Station, TX 77843.
We have previously shown that a conditioned antinociception can be established and extinguished in the spinalized rat (Grau et al., Beh. Neurosci., 104, 489, 1990). The present study explored whether this conditioned response would exhibit latent inhibtion and overshadowing. In both experiments testing was conducted 24 hr after subjects received a spinal transection at T2. Mild shock to the left or right paw served as the conditioned stimulus (CS). The unconditioned stimulus (US) was an intense tail-shock. Antinociception during the CS was assessed with the tail-flick test 1 hr after training. To show latent inhibition subjects were preexposed to either the CS+. CS- or nothing (n=10). All of the subjects the received differential conditioning in which one CS (the CS+) was paired with the US while the other was presented alone (the CS-). WE found that preexposure to either the CS+ or CS- attenuated classical conditioning. To test for overshadowing subjects recieved either: 1) a mild CS paired with the US; 2) the mild CS plus a strong CS paired with the US; or 3) the mild CS and US unpaired. Only subjects in the first training condition exhibited conditined antinociception. Supported by BNS 881981 to J.W.G.
Published in Society for Neuroscience Abstracts, 16, 1990.