Delayed development of fear-potentiated startle in rats.
The developmental emergence of fear-potentiated startle was examined in rats ranging in age from 16 to 75 days. In Experiment 1, a pure tone served as the conditioned stimulus (CS) and an acoustic startle pulse served as the unconditioned stimulus (US) for fear conditioning. Fear-potentiated startle by the tone CS was observed in rats 23 days of age and older but not in rats 16 days of age. In Experiment 2, a light served as the CS. Rats 30 days of age and older showed fear-potentiated startle, whereas 23-day-old rats did not. The final experiment demonstrated that another behavioral index of fear, stimulus-elicited freezing, was observed earlier in development than fear-potentiated startle, confirming the effectiveness of the training procedure for conditioning fear. The results suggest that fear-potentiated startle is a relatively late-emerging response system, paralleling the development of conditioned autonomic changes (e.g., heart rate) rather than that of freezing.
Hunt
P S
PS
Department of Psychology, Princeton University, New Jersey 08544-1010.
Richardson
R
R
Campbell
B A
BA
D000375:Aging / Q000523:psychology*; D000818:Animals; D001143:Arousal; D001245:Association Learning; D003214:Conditioning, Classical; D005239:Fear; D005260:Female; D006185:Habituation, Psychophysiologic; D006339:Heart Rate; D008297:Male; D008570:Memory, Short-Term; D009043:Motor Activity; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time; D013216:Reflex, Startle; D014796:Visual Perception