Associative regulation of Pavlovian fear conditioning: unconditional stimulus intensity, incentive shifts, and latent inhibition.
Conditional stimuli (CS) associated with painful unconditional stimuli (US) produce a naloxone-reversible analgesia. The analgesia serves as a negative-feedback regulation of fear conditioning that can account for the impact of US intensity and CS predictiveness on Pavlovian fear conditioning. In Experiment 1 training under naloxone produced learning curves that approached the same high asymptote despite US intensity. Shifting drug treatment during acquisition had effects that paralleled US intensity shifts. In Experiment 3 naloxone reversed Hall-Pearce (1979) negative transfer using a contextual CS, indicating that conditional analgesia acquired during the CS-weak-footshock phase retards acquisition in the CS-strong-footshock phase. Experiment 5 used a tone CS in both a latent-inhibition and a negative-transfer procedure. Only negative transfer was blocked by naloxone. Therefore, negative transfer but not latent inhibition is mediated by a reduction of US processing.
Young
S L
SL
Department of Psychology, University of California, Los Angeles 90024-1563.
Fanselow
M S
MS
D000818:Animals; D001143:Arousal / Q000187:drug effects; D001245:Association Learning / Q000187:drug effects*; D003214:Conditioning, Classical / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005239:Fear / Q000187:drug effects*; D005260:Female; D011939:Mental Recall / Q000187:drug effects; D009042:Motivation; D009043:Motor Activity / Q000187:drug effects; D009270:Naloxone / Q000494:pharmacology*; D051381:Rats; D014163:Transfer, Psychology
D009270:Naloxone