Effect of Conditioned Fear on Responsiveness to Hyperalgesia in Rats

Author: Shuh-Ren Jin

Abstract：

A number of recent research studies have suggested that the response of pain to electric shock can be conditioned. However, mixed results stemmed from these studies producing either conditioned analgesia (insensitivity to pain) or hyperalgesia when triggered by various conditioned stimuli. The present study hypothesized that psychogenic hyperalgesia can be triggered by conditioned fear as measured by tailflick latencies. In the present experiment, rats (N=22) were exposed to shock an equal number of times in conditioning sessions. Separate groups were then tested either with or without a conditioned fear stimulus (CS) in a tail-flick test. The hypothesis was supported. It was found that a fear CS appeared to produce significantly (p<.01) decreased tail -flick latencies indicating a hyperalgesic response. The nature of the tail-flick reflex and the procedures used by studies producing the various findings were discussed.

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