Journal Article

Evoked oscillatory cortical activity during acute pain: Probing brain in pain by transcranial magnetic stimulation combined with electroencephalogram

De Martino, Enrico, Casarotto, Silvia, de Andrade, Daniel Ciampi, Couto, Bruno Andry, Rosanova, Mario, Graven‐Nielsen, Thomas, Casali, Adenauer, Hassan, Gabriel

2024

Overview

Temporal dynamics of local cortical rhythms during acute pain remain largely unknown. The current study used a novel approach based on transcranial magnetic stimulation combined with electroencephalogram (TMS‐EEG) to investigate evoked‐oscillatory cortical activity during acute pain. Motor (M1) and dorsolateral prefrontal cortex (DLPFC) were probed by TMS, respectively, to record oscillatory power (event‐related spectral perturbation and relative spectral power) and phase synchronization (inter‐trial coherence) by 63 EEG channels during experimentally induced acute heat pain in 24 healthy participants. TMS‐EEG was recorded before, during, and after noxious heat (acute pain condition) and non‐noxious warm (Control condition), delivered in a randomized sequence. The main frequency bands (α, β1, and β2) of TMS‐evoked potentials after M1 and DLPFC stimulation were recorded close to the TMS coil and remotely. Cold and heat pain thresholds were measured before TMS‐EEG. Over M1, acute pain decreased α‐band oscillatory power locally and α‐band phase synchronization remotely in parietal–occipital clusters compared with non‐noxious warm (all p < .05). The remote (parietal–occipital) decrease in α‐band phase synchronization during acute pain correlated with the cold (p = .001) and heat pain thresholds (p = .023) and to local (M1) α‐band oscillatory power decrease (p = .024). Over DLPFC, acute pain only decreased β1‐band power locally compared with non‐noxious warm (p = .015). Thus, evoked‐oscillatory cortical activity to M1 stimulation is reduced by acute pain in central and parietal–occipital regions and correlated with pain sensitivity, in contrast to DLPFC, which had only local effects. This finding expands the significance of α and β band oscillations and may have relevance for pain therapies. We used a novel approach that combines transcranial magnetic stimulation with an electroencephalogram (known as TMS‐EEG) to study evoked‐oscillatory cortical activity during acute pain. Our main findings showed that alpha oscillations, evoked by M1 probing, were reduced during acute pain, which correlated with individual trait pain sensitivity.

• Publisher: John Wiley & Sons, Inc
• Subject: acute pain / Acute Pain - physiopathology / Acute Pain - therapy / Adult / alpha / Dorsolateral Prefrontal Cortex - physiology / Dorsolateral Prefrontal Cortex - physiopathology / electroencephalogram / Electroencephalography - methods / event‐related spectral perturbation / Female / Hot Temperature / Humans / inter‐trial coherence / Male / Motor Cortex - physiology / Motor Cortex - physiopathology / Pain Threshold - physiology / transcranial magnetic stimulation / Transcranial Magnetic Stimulation - methods / Young Adult