THE IMPORTANCE OF EQUATING FLEXION FORCE WHEN MANIPULATIONS OF TEMPORAL CONTIGUITY ELIMINATE "INSTRUMENTAL LEARNING" IN SPINALIZED RATS. D.G. Barstow, J.W. Grau*, R.L. Joynes, T.W. Prentice. Dept. of Psychology, Texas A&M Univ., College Station, TX 77843.
Evidence suggests spinal mechanisms are capable of supporting instrumental conditioning. In these experiments, subjects can terminate shock to the hind leg by exhibiting a flexion response. In previous studies (Neurosci. Abs. 19, 408.16), we have shown that Escape/Yoke differences arise when paired subjects are equated for flexion force. However it was unclear what mechanisms of learning underlie the acquisition of this response. In the present study, we show that disruption of temporal contiguity eliminates the acquisition of the flexion response.
Within 18-48 hours after subjects (N=18) received a spinal transection at T2, they were placed in restraining tubes. Shock intensity was then adjusted so that it elicited a flexion with a force of 0.6 N. Three groups of subjects then experienced a 30 m training session in which they received a 100 msec delay in onset, 100 msec delay in offset, or 0 msec delay in shock delivery. Subjects in the 0 msec delay group, but not in the 100 msec delay groups, exhibited a leg flexion response that prevented delivery of shock. At the end of training, response force was again equated across subjects. All subjects then experienced a testing session in which they received 30 m of 0 msec delay shock. Subjects previously exposed to a delay in either onset or offset of shock failed to acquire a flexion response. These results indicate that Supported by MH48994 to J.W.G.
Published in Society for Neuroscience Abstracts, 20, 1994, 787.