EEG oscillations reveal neuroplastic changes in pain processing associated with long-term meditation.

Long-term meditation practice is associated with a proactive top-down inhibition of brain regions that process the sensory aspects of pain, even when the meditator is not actively meditating. Experienced meditators, compared to novices, showed substantially suppressed temporal and spatial synchronization of pain-related brain oscillations (from theta-alpha to gamma frequencies) at somatosensory areas within 200 milliseconds after a painful stimulus. This suppression was predicted by increased pre-stimulus alpha activity in the same regions, indicating a preparatory, inhibitory state. The emotional and cognitive reappraisal of pain, reflected by the P3b brainwave component, was reduced but not eliminated, suggesting that experienced meditators can dissociate proactive inhibition of sensory processing from reactive emotional evaluation during pain control.

Study at a glance

Abstract

The experience of pain is a combined product of bottom-up and top-down influences mediated by attentional and emotional factors. Meditation states and traits are characterized by enhanced attention/emotion regulation and expanded self-awareness that can be expected to modify pain processing. The main objective of the present study was to explore the effects of long-term meditation on neural mechanisms of pain processing. EEG pain-related oscillations (PROs) were analysed in highly experienced practitioners and novices during a non-meditative resting state with respect to (a) local frequency-specific and temporal synchronizing characteristics to reflect mainly bottom-up mechanisms, (b) spatial synchronizing patterns to reflect the neural communication of noxious information, (c) pre-stimulus oscillations to reflect top-down mechanisms during pain expectancy, and (d) the P3b component of the pain-related potential to compare the emotional/cognitive reappraisal of pain events by expert and novice meditators. Main results demonstrated that in experienced (long-term) meditators as compared to non-experienced (short-term) meditators (1) the temporal and spatial synchronizations of multispectral (from theta-alpha to gamma) PROs were substantially suppressed at primary and secondary somatosensory regions contra-lateral to pain stimulation within 200 ms after noxious stimulus; (2) pre-stimulus alpha activity was significantly increased at the same regions, which predicted the suppressed synchronization of PROs in long-term meditators; (3) the decrease of the P3b component was non-significant. These novel observations provide evidence that even when subjected to pain outside of meditation, experienced meditators exhibit a pro-active top-down inhibition of somatosensory areas resulting in suppressed processing and communication of sensory information at early stages of painful input. The emotional/cognitive appraisal of pain is reduced but remains preserved revealing a capacity of experienced meditators to dissociate pro-active and reactive top-down processes during pain control.