An immediate-shock freezing deficit with discrete cues: a possible role for unconditioned stimulus processing mechanisms.
Five experiments with C57BL/6 mice (Mus musculus) investigated whether failures in shock processing might contribute to deficits in freezing that occur after an animal receives a shock immediately on exposure to a conditioning context. Experiment 1 found that more contextual freezing resulted from delayed shocks than from immediate shocks across 4 shock intensities. Experiment 2 extended the immediate-shock freezing deficit to discrete stimuli. Experiment 3 found that preexposure to the to-be-conditioned cue did not facilitate immediate cued conditioning. Experiment 4 found that context preexposure enhanced context-evoked fear after an immediate shock. Experiment 5 found that context preexposure also enhanced immediate cued conditioning. These findings are problematic for current theories of the immediate-shock freezing deficit that focus exclusively on processing of the conditioned stimulus, and they suggest that failures in shock processing may contribute to the deficit.
Lattal
K M
KM
Department of Biology, 3740 Hamilton Walk, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA. kmlattal@sas.upenn.edu
Abel
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D000818:Animals; D003213:Conditioning, Psychological / Q000502:physiology*; D003463:Cues; D005260:Female; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010468:Perceptual Disorders / Q000175:diagnosis*; D011597:Psychomotor Performance / Q000502:physiology*; D012769:Shock / Q000523:psychology*