Amygdala activity contributes to the dissociative effect of cannabis on pain perception

Lee, Michael C., Ploner, Markus, Wiech, Katja, Bingel, Ulrike, Wanigasekera, Vishvarani, Brooks, Jonathan ORCID:, Menon, David K. and Tracey, Irene (2013) Amygdala activity contributes to the dissociative effect of cannabis on pain perception. Pain, 154 (1). pp. 124-134. ISSN 0304-3959

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Cannabis is reported to be remarkably effective for the relief of otherwise intractable pain. However, the bases for pain relief afforded by this psychotropic agent are debatable. Nonetheless, the frontal-limbic distribution of cannabinoid receptors in the brain suggests that cannabis may target preferentially the affective qualities of pain. This central mechanism of action may be relevant to cannabinoid analgesia in humans, but has yet to be demonstrated. Here, we employed functional magnetic resonance imaging to investigate the effects of delta-9-tetrahydrocannabinol (THC), a naturally occurring cannabinoid, on brain activity related to cutaneous ongoing pain and hyperalgesia that were temporarily induced by capsaicin in healthy volunteers. On average, THC reduced the reported unpleasantness, but not the intensity of ongoing pain and hyperalgesia: the specific analgesic effect on hyperalgesia was substantiated by diminished activity in the anterior mid cingulate cortex. In individuals, the drug-induced reduction in the unpleasantness of hyperalgesia was positively correlated with right amygdala activity. THC also reduced functional connectivity between the amygdala and primary sensorimotor areas during the ongoing-pain state. Critically, the reduction in sensory-limbic functional connectivity was positively correlated with the difference in drug effects on the unpleasantness and the intensity of ongoing pain. Peripheral mechanisms alone cannot account for the dissociative effects of THC on the pain that was observed. Instead, the data reveal that amygdala activity contributes to interindividual response to cannabinoid analgesia, and suggest that dissociative effects of THC in the brain are relevant to pain relief in humans.

Item Type: Article
Additional Information: Funding Information: M.C. Lee and project costs are supported by a Medical Research Council Clinical Research Training Fellowship ( RG47261-RUAG/020 ) as well as funding from the Wellcome Trust (Oxford Centre for Functional MRI of the Brain) and the National Institute for Health Research Oxford Biomedical Research Centre. We thank Dr. Philip Hu for assistance with the clinical monitoring of subjects.
Uncontrolled Keywords: amygdala,brain,cannabinoids,fmri,humans,hyperalgesia,pain,neurology,clinical neurology,anesthesiology and pain medicine ,/dk/atira/pure/subjectarea/asjc/2800/2808
Faculty \ School: Faculty of Social Sciences > School of Psychology
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Depositing User: LivePure Connector
Date Deposited: 07 Sep 2022 11:31
Last Modified: 21 Oct 2022 01:35
DOI: 10.1016/j.pain.2012.09.017

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