Prefrontal cortico-thalamic regulation of pain by mindfulness meditation

Abstract

Mindfulness meditation reliably reduces pain. We have repeatedly found that mindfulness-based analgesia is associated with thalamic deactivation and prefrontal-cortical (PFC) activation. Our working theoretical model proposes that mindfulness-induced shifts in executive attention facilitate pain-relief by PFC-driven thalamic inhibition to reduce the elaboration of nociception throughout the cortex. Yet, there are no studies that have identified neuro-functional connections supporting mindfulness meditation-based pain relief. The proposed study tested if mindfulness-based analgesia is associated with stronger a) PFC-thalamic connectivity and b) thalamic decoupling with lower-level nociceptive targets in somatosensory cortices. Forty healthy, pain-free volunteers were randomized to a 4-session (20-minutes each) mindfulness training or book-listening control group (n=20/group). After their respective interventions, four total “heat” series (ten, 10-second plateaus of 49°C) were administered to the right calf during functional MRI (fMRI) acquisition (2-rest vs. 2-meditation). Pain intensity and unpleasantness ratings (11-point visual analog scale) were collected after each series. Seed based connectivity analyses (pre-registered: NCT03414138) were carried out with a contralateral thalamic seed corresponding to peak deactivation correlates of meditation-related analgesia derived from our previous study. For each participant, mean time course values corresponding to the seed per heat fMRI-series were entered as regressors to identify significant seed-to-whole brain voxel correlations and covariation with pain reports. Mindfulness produced (p