Conditioned inhibition of fear-potentiated startle and skin conductance in humans.
Conditioned inhibition of classical conditioning was investigated with the startle reflex and the skin conductance response (SCR) in humans using a serial presentation of the conditioned inhibitor (X) and of the conditioned stimulus (CS). The unconditioned stimulus (US) was a shock. During conditioning, participants were presented with two different reinforced CS (A, B) and with X preceding A (noted X-->A). During X-->A, A was not reinforced with the US. During the summation test, B, X-->B, and Y-->B were presented (Y was a new stimulus that tested the specificity of the inhibitory properties of X). B was not reinforced during the summation test. A, B, X, and Y were lights of different colors. Participants were divided into a low and a high anxious group based on the TPQ (C.R. Cloninger, 1987). In the low anxious group, conditioned startle potentiation and SCR responses to A were inhibited when X preceded A (noted A(XA)). This differential responding to A and A(XA) emerged earlier with the SCR than with startle. During the summation test, the inhibitory properties of X did not transfer to B. In the high anxious group, there was only a differential SCR to A and A(XA). X did not inhibit startle potentiation to A.
Grillon
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Department of Psychiatry, Yale University School of Medicine, New Haven, USA. christian.grillon@nih.gov
Ameli
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D000293:Adolescent; D000328:Adult; D004576:Electromyography; D005239:Fear / Q000502:physiology*; D005260:Female; D005712:Galvanic Skin Response / Q000502:physiology*; D006185:Habituation, Psychophysiologic; D006801:Humans; D008297:Male; D013216:Reflex, Startle / Q000502:physiology*