Summary
The effects of a number of drugs on conditioned and unconditioned arousal responses (behavioural and electroencephalographic) produced by auditory stimuli in cats are reported. Positive conditioning was achieved by pairing certain auditory stimuli with a painful stimulus (electric shock).
Chlorpromazine increased thresholds for both conditioned and unconditioned stimuli and eventually blocked arousal responses completely. Reserpine, which had a delayed effect, caused only a slight rise in the conditioned response but blocked the unconditioned response although this latter effect may have been in part due to habituation.
Amphetamine caused a fall in the threshold for unconditioned arousal responses but did not change that for conditioned responses. However, these thresholds could no longer be assessed when doses which produced full alerting were used.
LSD 25 also caused a fall in the threshold for arousal to unconditioned stimulus and no change in the conditioned response, but it restored the response to a stimulus which had previously been habituated.
The results are discussed in relation to the hypothesis for the sites of action of these drugs in the brain which has been expounded previously.
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This work has been sponsored by the Office of Scientific Research of the Air Research and Development Command, United States Air Force, Contract No. AF 61 (514)-1184.
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Key, B.J., Bradley, P.B. The effects of drugs on conditioning and habituation to arousal stimuli in animals. Psychopharmacologia 1, 450–462 (1960). https://doi.org/10.1007/BF00429270
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DOI: https://doi.org/10.1007/BF00429270