Cortical oscillatory changes during thermal grill illusion

Abstract

Objective The thermal grill illusion (TGI) can cause a burning pain sensation when the skin is subjected to simultaneously harmless hot and cold stimuli, and the pain is reported to be similar to central neuropathic pain. Although electroencephalography (EEG) is commonly used in pain research, no reports have revealed EEG activity during TGI. Methods One healthy subject was enrolled, and EEG activity was recorded during the experience of the TGI and a warm sensation. Independent component analysis (ICA) was applied to preprocessed EEG data, which was divided into several clusters. Results Theta and alpha bands in the insular cortex and parietal operculum clusters were significantly more desynchronized under the TGI condition than under the warm condition (P < 0.05). Additionally, theta, alpha and beta bands in the frontal (middle and inferior frontal gyrus) cluster showed significantly more desynchronization under the TGI condition than under the warm condition (P < 0.05). Conclusion EEG oscillations in these brain areas could be useful markers of central neuropathic pain.