Placebo and Opioid Analgesia-- Imaging a Shared Neuronal Network

TLDR

Placebo analgesia is thought to engage higher‑order cognitive networks and endogenous opioid systems, with the rostral anterior cingulate cortex and brainstem implicated in both opioid and placebo pain relief. Positron emission tomography revealed that both opioid and placebo analgesia increase activity in the rostral anterior cingulate cortex. The study found that rACC activity covaried with brainstem activity during opioid and placebo analgesia but not during pain alone, indicating a shared neural mechanism.

Abstract

It has been suggested that placebo analgesia involves both higher order cognitive networks and endogenous opioid systems. The rostral anterior cingulate cortex (rACC) and the brainstem are implicated in opioid analgesia, suggesting a similar role for these structures in placebo analgesia. Using positron emission tomography, we confirmed that both opioid and placebo analgesia are associated with increased activity in the rACC. We also observed a covariation between the activity in the rACC and the brainstem during both opioid and placebo analgesia, but not during the pain-only condition. These findings indicate a related neural mechanism in placebo and opioid analgesia.