Amygdala lesions produce analgesia in a novel, ethologically relevant acute pain test

M. A. Hebert, D. Ardid, J. A. Henrie, K. Tamashiro, D. C. Blanchard, R. J. Blanchard

Research output: Contribution to journalArticlepeer-review

Abstract

Acute pain tests using mechanical stimuli typically do not involve objects important in the evolutionary history of the subjects, and may fail to evaluate the contribution of biobehavioral defensive reactions to the total pain response. Spines are common structural defenses that protect plants and animals against predation. The present studies examined the reaction to contact with such natural, mechanical pain stimuli in the laboratory rat, utilizing a floor board with protruding pins located in the middle of a novel alley (the 'fakir' test). Behavioral responses were characterized in 10-min tests (Experiment 1). Subjects showed voluntary contact with the pins followed by patterns of avoidance and risk assessment (stretch attend and stretch approach). Few subjects crossed the array of pins. The amygdala has been implicated in the perception of pain, particularly in stressful or fearful contexts. In Experiment 2, the fakir test was used to examine, concurrently, the effects of amygdala lesions on analgesiometric (frequency and duration of pin crossings) and anxiometric (risk assessment) measures. Large, bilateral, lesions of the amygdala significantly increased both the number of pin crossings and time spent on the pins without affecting the risk assessment measures. These findings suggest a possible dissociation between anxiety and pain perception with an important (nonaffective) role for the amygdala in the latter. Copyright (C) 1999 Elsevier Science Inc.

Original languageEnglish (US)
Pages (from-to)99-105
Number of pages7
JournalPhysiology and Behavior
Volume67
Issue number1
DOIs
StatePublished - Aug 1 1999
Externally publishedYes

Keywords

  • Amygdala-Anxiety
  • Analgesia
  • Defense
  • Pain models
  • Risk assessment

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology
  • Behavioral Neuroscience

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