Gamma band oscillations reflect sensory and affective dimensions of pain

TL;DR

This study investigates how gamma band oscillations in EEG relate to the sensory and emotional aspects of pain, revealing distinct early and late oscillatory responses linked to pain perception and affective modulation.

Contribution

It identifies two gamma oscillation patterns associated with pain processing and emotional modulation, advancing understanding of neural mechanisms underlying pain's multidimensional nature.

Findings

Early GBO correlates with pain intensity and unpleasantness.

Late GBO is larger for negative emotional primes and correlates with pain unpleasantness.

Emotion modulates pain unpleasantness but not intensity.

Abstract

Pain is a multidimensional process, which can be modulated by emotions, however, the mechanisms underlying this modulation are unknown. We used pictures with different emotional valence (negative, positive, neutral) as primes and applied electrical painful stimuli as targets to healthy participants. We assessed pain intensity and unpleasantness ratings and recorded electroencephalograms (EEG). We found that pain unpleasantness, and not pain intensity ratings were modulated by emotion, with increased ratings for negative and decreased for positive pictures. We also found two consecutive gamma band oscillations (GBOs) related to pain processing from time frequency analyses of the EEG signals. An early GBO had a cortical distribution contralateral to the painful stimulus, and its amplitude was positively correlated with intensity and unpleasantness ratings, but not with prime valence. The late GBO had a centroparietal distribution and its amplitude was larger for negative compared to neutral and positive pictures. The emotional modulation effect (negative versus positive) of the late GBO amplitude was positively correlated with pain unpleasantness. The early GBO might reflect the overall pain perception, possibly involving the thalamocortical circuit, while the late GBO might be related to the affective dimension of pain and top-down related processes.