(112) - Patient-clinician brain concordance in social mirroring circuitry supports placebo analgesia during pain treatment: a fMRI hyperscanning study

Abstract

The patient-clinician relationship can shape pain, but the brain basis for this is unknown. We simultaneously recorded functional Magnetic Resonance Imaging (fMRI hyperscanning) in patient-clinician dyads, who interact via video transfer, during clinician-initiated treatment of patients' pain. We hypothesized concordant activation of circuitry involved in social mirroring, such as ventrolateral Prefrontal Cortex (vlPFC) and anterior Insula (aINS) in both patients and clinicians during pain treatment. Patients with chronic pain (fibromyalgia) and clinicians (acupuncturists) were enrolled. Each patient was matched with a clinician participant (17 patient-clinician ‘dyads’). The patient received a number of moderately painful cuff pressures to the left leg (15 s), while the clinician used a button box to control (real/sham) electro-acupuncture stimulation to reduce cuff pain. Both participants rated self-pain (patients) or vicarious pain (clinicians) after each trial. Using MRI-compatible cameras, participants were enabled to communicate non-verbally throughout the scan. fMRI preprocessing included motion correction, skull stripping, magnetic field inhomogeneity correction, and MNI152 registration. After single-subject general linear modeling, we conducted a group GLM (whole-brain cluster-corrected) followed by a group conjunction analysis, between patients and clinicians, of the [pain + treatment] > [rest] contrast. Patients' pain significantly decreased during both real and sham treatment compared to overt no-treatment, which corresponded with lower vicarious pain ratings by clinicians (pain + treatment, relative to no-treatment). Furthermore, patients' placebo analgesia (no-treat—sham) correlated with clinicians' estimation of patients' pain reduction (no-treat—sham). A conjunction analysis of patients' (evoked pain + treatment) and clinicians (observing pain + treating) brain response demonstrated activation of vlPFC, aINS, and temporoparietal junction (TPJ), for both patients and clinicians. Using ROI extraction from the group vlPFC conjunction mask, we found that the number of co-activated voxels (treat—no-treat) between patients and clinicians correlated with patients' placebo analgesia, within dyads. Thus, increased patient-clinician concordance in vlPFC may support socially facilitated placebo analgesia.