Amygdala Lesions Produce Analgesia in a Novel, Ethologically Relevant Acute Pain Test

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 a...

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Bibliographic Details
Published in:Physiology & behavior 1999-08, Vol.67 (1), p.99-105
Main Authors: Hebert, M.A, Ardid, D, Henrie, J.A, Tamashiro, K, Blanchard, D.C, Blanchard, R.J
Format: Article
Language:English
Subjects:
Amygdala - physiology
Amygdala—Anxiety
Analgesia
Anatomical correlates of behavior
Animals
Attention - physiology
Avoidance Learning - physiology
Behavioral psychophysiology
Biological and medical sciences
Brain Mapping
Defense
Ethology
Fear - physiology
Fundamental and applied biological sciences. Psychology
Male
Mechanoreceptors - physiology
Pain models
Pain Threshold - physiology
Psychology. Psychoanalysis. Psychiatry
Psychology. Psychophysiology
Rats
Rats, Long-Evans
Risk assessment
Risk-Taking
Space life sciences
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Summary: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.
ISSN:0031-9384
1873-507X
DOI:10.1016/S0031-9384(99)00042-6