Temporal specificity of fear conditioning: effects of different conditioned stimulus-unconditioned stimulus intervals on the fear-potentiated startle effect.
Separate groups of rats were given 30 pairings of a light (conditioned stimulus, CS) and 500-ms shock (unconditioned stimulus, US) at CS-US intervals of 0, 25, 50, 100, 200, 800, 3,200, 12,800, or 51,200 ms. Other groups had lights and shocks inconsistently paired. The startle reflex was elicited 2-4 days later with a noise burst alone or 25-51,200 ms after light onset. After CS-US pairings over a wide range of intervals (25-51,200 ms), startle was potentiated in testing, sometimes as rapidly as 50 ms after light onset. Magnitude of potentiation and resistance to extinction were generally greater with longer CS-US intervals. In several groups, potentiation was maximal at a test interval that matched the CS-US interval used in training. This temporal specificity sharpened with increasing numbers of training trials but even occurred with a single training trial in which a 51,200-ms CS-US interval was used. The data indicate that even during simple fear conditioning, animals rapidly learn a temporal CS-US relationship. This has important implications for understanding the neural mechanisms of fear conditioning.
Davis
M
M
Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut 06508.
Schlesinger
L S
LS
Sorenson
C A
CA
D000818:Animals; D001143:Arousal; D001245:Association Learning; D001288:Attention; D003214:Conditioning, Classical; D004597:Electroshock; D005108:Extinction, Psychological; D005239:Fear; D007858:Learning; D008297:Male; D008568:Memory; D011939:Mental Recall; D051381:Rats; D011919:Rats, Inbred Strains; D013216:Reflex, Startle; D013998:Time Perception