ORIGINAL RESEARCH article
Front. Hum. Neurosci.
Sec. Brain Imaging and Stimulation
Volume 19 - 2025 | doi: 10.3389/fnhum.2025.1546414
This article is part of the Research TopicThe Role of Neural Oscillations in translational Pain researchView all 3 articles
Distinct resting state neural activity in chronic pain patients who respond to transcranial electric stimulation (tES) for pain relief
Provisionally accepted
Alba Fernández1,2*
Lara Rubal-Otero2,3Antonio Gil-Ugidos1,2
Diego Pinal1,2
Alberto Jacobo González-Villar4
María Teresa Carrillo-de-la-Peña1,2- 1Institute of Psychology (IPsiUS), Universidade de Santiago de Compostela, Santiago de Compostela, Spain
- 2Brain and Pain (BaP) Lab, Department of Clinical Psychology and Psychobiology, University of Santiago de Compostela (USC), Santiago de Compostela, Spain., Santiago de Compostela, Spain
- 3Foundation for Health Research Institute of Santiago de Compostela (FIDIS), Santiago de Compostela, Spain., Santiago de Compostela, Spain
- 4Psychological Neuroscience Laboratory, Center for Research in Psychology, University of Minho, Braga, Braga, Portugal
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Transcranial electric stimulation (tES) techniques have shown promising results for pain relief in chronic pain. However, little is known about the mechanisms by which these non-invasive neuromodulation techniques produce analgesic effects. Besides, previous studies underscore the need to identify profiles of patients with a better response to tES. In this randomized clinical trial (ClinicalTrials.gov: NCT05099406), we studied whether tES modulate brain oscillatory activity by recording resting state EEG (eyes open) from 106 chronic pain patients before and after a 15-day home-based intervention with either transcranial direct or alternate current stimulation, or sham stimulation. Power spectral density (PSD) at rest was analyzed in the theta, alpha, and beta frequency bands, in two 2x2 designs with the factor time (pre vs. post intervention session) and group, with each active tES condition being compared against the sham stimulation. Additionally, we compared responders vs non-responders to active tES (according to their reported pain relief after the intervention) in the same PSD indices. The analysis showed that the intervention had no significant effects on PSD in any band, and thus revealed that understanding the physiological mechanisms of the analgesic effects of tES remains a pending matter. However, higher PSD in the theta band was observed for responders compared to non-responders regardless of the assessment session. This finding suggests that the theta-band oscillatory activity of patients with chronic pain could be a promising prognostic biomarker for the effectiveness of tES and opens a new avenue for individualizing tES interventions.
Keywords: Chronic Pain, transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), Electroencephalography, Power spectral density (PSD)
Received: 16 Dec 2024; Accepted: 07 May 2025.
Copyright: © 2025 Fernández, Rubal-Otero, Gil-Ugidos, Pinal, González-Villar and Carrillo-de-la-Peña. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Alba Fernández, Institute of Psychology (IPsiUS), Universidade de Santiago de Compostela, Santiago de Compostela, Spain
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