Spectral and spatial changes of brain rhythmic activity in response to the sustained thermal pain stimulation

Abstract

The aim of this study was to investigate the neurophysiological correlates of pain caused by sustained thermal stimulation. A group of 21 healthy volunteers was studied. 64-channel continuous EEG was recorded while the subject received tonic thermal stimulation. Spectral changes extracted from EEG were quantified and correlated with pain scales reported by subjects, the stimulation intensity, and the time course. Network connectivity was assessed to study the changes in connectivity patterns and strengths among brain regions that have been previously implicated in pain processing. Spectrally, a global reduction in power was observed in the lower spectral range, from delta to alpha, with the most marked changes in the alpha band. Spatially, the contralateral region of the somatosensory cortex, identified using source localization, was most responsive to stimulation status. Maximal desynchrony was observed when stimulation was present. The degree of alpha power reduction was linearly correlated to the pain rating reported by the subjects. Contralateral alpha power changes appeared to be a robust correlate of pain intensity experienced by the subjects. Granger causality analysis showed changes in network level connectivity among pain-related brain regions due to high intensity of pain stimulation versus innocuous warm stimulation. These results imply the possibility of using noninvasive EEG to predict pain intensity and to study the underlying pain processing mechanism in coping with prolonged painful experiences. Once validated in a broader population, the present EEG-based approach may provide an objective measure for better pain management in clinical applications.

Neural oscillations and connectivity characterizing the state of tonic experimental pain in humans

“…Although these frequencies have been implicated in the top‐down signaling of predictions (Fries, ; Michalareas et al, ; Ploner et al, ), the present findings indicate that the alpha connectivity between sensorimotor and prefrontal cortex might reflect increased bottom‐up rather than top‐down signaling of potentially nociceptive information as our recent work suggests (Nickel, May, Tiemann, Schmidt, et al, ). These results are in line with previous findings showing that directed functional connectivity is enhanced between somatosensory and medial frontal cortex during pain (Huishi Zhang et al, ). Moreover, the findings are in accordance with mounting evidence for an important role of the medial prefrontal cortex for the encoding of chronic (Baliki et al, ; Hashmi et al, ; Vachon‐Presseau et al, ) and tonic experimental pain (Nickel, May, Tiemann, Schmidt, et al, ; Schulz et al, ).…”

“…These results are in line with previous findings showing that directed functional connectivity is enhanced between somatosensory and medial frontal cortex during pain (Huishi Zhang et al, 2016). Moreover, the findings are in accordance with mounting evidence for an important role of the medial prefrontal cortex for the encoding of chronic (Baliki et al, 2006;Hashmi et al, 2013;Vachon-Presseau et al, 2016) and tonic experimental pain (Nickel, May, Tiemann, Schmidt, et al, 2017;Schulz et al, 2015).…”

“…Comparatively few electroencephalography (EEG), magnetoencephalography (MEG), and intracranial recordings have investigated the brain processing of tonic experimental pain stimuli. They have shown local suppressions of alpha and beta oscillations in sensorimotor cortices (Colon, Liberati, & Mouraux, 2017;Giehl, Meyer-Brandis, Kunz, & Lautenbacher, 2014;Huishi Zhang, Sohrabpour, Lu, & He, 2016;Nickel, May, Tiemann, Schmidt, et al, 2017;Nir, Sinai, Moont, Harari, & Yarnitsky, 2012;Peng, Hu, Zhang, & Hu, 2014;Schulz et al, 2015) and insula (Liberati et al, 2019) as well as increases of gamma oscillations in prefrontal areas (Nickel, May, Tiemann, Schmidt, et al, 2017;Peng et al, 2014;Schulz et al, 2015). Some studies revealed changes of the peak frequency of neural oscillations (Furman et al, 2018;Nir, Sinai, Raz, Sprecher, & Yarnitsky, 2010).…”

Characterization of functional brain activity and connectivity using EEG and fMRI in patients with sickle cell disease

“…The increased temporal and spatial resolution of this method makes it desirable to further probe for markers of disease severity and potentially chronic pain that can be used to improve treatment strategies. Non-invasive imaging studies have shown it is possible to use biomarkers to objectively rate acute pain in healthy controls (Zhang et al, 2016, Wager et al, 2013). Similar techniques could be applied to chronic pain patients so that pain can be objectively measured to improve treatment and reduce the risk of opioid therapy.…”

Quantifying and Characterizing Tonic Thermal Pain Across Subjects From EEG Data Using Random Forest Models

“…However, most of these studies have investigated the effects of phasic pain stimuli. To mimic responses triggered during chronic pain [26], there are a growing number of studies using tonic thermal stimuli [27]–[31]. …”