Hippocampus mediates nocebo impairment of opioid analgesia through changes in functional connectivity.

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Abstract

The neural mechanisms underlying placebo analgesia have attracted considerable attention over the recent years. In contrast, little is known about the neural underpinnings of a nocebo-induced increase in pain. We previously showed that nocebo-induced hyperalgesia is accompanied by increased activity in the hippocampus that scaled with the perceived level of anxiety. As a key node of the neural circuitry of perceived threat and fear, the hippocampus has recently been proposed to coordinate defensive behaviour in a context-dependent manner. Such a role requires close interactions with other regions involved in the detection of and responses to threat. Here, we investigated the functional connectivity of the hippocampus during nocebo-induced hyperalgesia. Our results show an increase in functional connectivity between hippocampus and brain regions implicated in the processing of sensory-discriminative aspects of pain (posterior insula and primary somatosensory/motor cortex) as well as the periaqueductal grey. This nocebo-induced increase in connectivity scaled with an individual's increase in anxiety. Moreover, hippocampus connectivity with the amygdala was negatively correlated with the pain intensity reported during nocebo hyperalgesia relative to the placebo condition. Our findings suggest that the hippocampus links nocebo-induced anxiety to a heightened responsiveness to nociceptive input through changes in its crosstalk with pain-modulatory brain areas.

Publication Date
2022-07
Online Publication Date
2022-06-16
Acceptance Date
2022-05-04
Keywords
amygdala, anxiety, brain, hippocampal, pain, Analgesia, Analgesics, Opioid, Hippocampus, Humans, Hyperalgesia, Magnetic Resonance Imaging, Nocebo Effect, Pain
Journal Title
Eur J Neurosci
Journal ISSN
0953-816X
1460-9568
Volume Title
Publisher
Wiley
Sponsorship
Deutsche Forschungsgemeinschaft (422744262‐TRR 289)
Wellcome Trust (203139/Z/16/Z)