EEG Spectral Analysis in Chronic Pain During Rest and Cognitive Reasoning.

Chronic pain (CP) represents a multidimensional condition in which cognitive and emotional factors shape the individual experience from perception to action. The purpose of this study was to characterize the functional significance of alterations in neural oscillatory dynamics underlying the transition from resting-state to cognitive load across distinct CP phenotypes. Continuous electroencephalographic data were acquired from patients with headache, migraine, and spine-related pain, as well as healthy controls, during rest and three visual-cognitive-motor (VCM) tasks: reaction time, working memory, and associative learning. First, within CP subgroups, we examined cognitive-load-related changes in oscillatory activity. In migraine patients, alpha/beta power attenuation induced during cognitive processing correlated with higher reported pain intensity. Relative to the spine-related pain group, migraine patients exhibited increased occipital alpha and gamma band activity during working memory and associative learning conditions, as a possible neurophysiological signature of cortical hyperexcitability. By comparing a subset of headache patients to healthy controls, we found elevated resting-state delta and gamma activity in the patient group. Under cognitive load conditions, headache patients showed higher power across delta, theta, beta, and gamma frequency bands. Delta and theta activity elicited during the working memory task correlated negatively with pain intensity. Our results demonstrate that the experience of chronic pain is accompanied by frequency-specific alterations in both resting and cognitive-associated oscillatory dynamics, reflecting impaired visual working-memory processing and top-down modulation of behaviorally relevant stimuli.