Gamma-Band Oscillations in the Primary Somatosensory Cortex—A Direct and Obligatory Correlate of Subjective Pain Intensity

Abstract

Electroencephalographic gamma band oscillations (GBOs) induced over the human primary somatosensory cortex (SI) by nociceptive stimuli have been hypothesized to reflect cortical processing involved directly in pain perception, because their magnitude correlates with pain intensity. However, as stimuli perceived as more painful are also more salient, an alternative interpretation of this correlation isthatGBOsreflectunspecificstimulus-triggeredattentionalprocessing.Infact,thisissuggestedbyrecentobservationsthatotherfeaturesofthe electroencephalographic (EEG) response correlate with pain perception when stimuli are presented in isolation, but not when their saliency is reduced by repetition. Here, by delivering trains of three nociceptive stimuli at a constant 1 s interval, and using different energies to elicit graded pain intensities, we demonstrate that GBOs recorded over SI always predict the subjective pain intensity, even when saliency is reduced by repetition. These results provide evidence for a close relationship between GBOs and the cortical activity subserving pain perception.

Ultra-low Noise EEG at LSBB: New results

“…Explaining this issue, it is worth mentioning that the average of the VAS pain ratings across all recordings and all subjects was 5.5 at the i-DUST 2016 hospital and 1.5 at LSBB, suggesting that despite the efforts to keep the experiment conditions equal, the subjects experienced more pain in the hospital facility than in LSBB. We might therefore hypothesize that the lower ratios in LSBB are caused by the lower pain experience in comparison with ICORD, which would in turn yield lower gamma band activity in LSBB as the strength of gamma band oscillations has been shown to correlate well with the intensity of the perceived pain [10]. However, since only a small number of subjects (two) were included for the heat task, caution must be exercised in interpreting the results pertaining to this task.…”

“…To reduce the disruptive effects of electrical interference and movement (i.e. noise), depending on the neuronal activity of interest, EEG is often band-pass filtered at different frequencies from 0.5 to 100 Hz and is then studied in terms of activity across different frequency bands; including (0-4 Hz), (4)(5)(6)(7), (8)(9)(10)(11)(12) Hz), (12-30 Hz), and (30-100 Hz). Clinically, EEG frequencies are most often studied from 0.5 to 30 Hz with the gamma ( ) band being ignored.…”

“…The gamma band is ignored due to the use of filters to suppress unwanted electromagnetic noise from powered (50 or 60 Hz) electrical outlets. In recent years however, the gamma band has received greater scrutiny and is typically known to underlie and be modulated by sensorimotor behaviors and internal cognitive processes such as working memory and attention [10].…”

Highly Energized Inhibitory Interneurons are a Central Element for Information Processing in Cortical Networks

“…16,19,23,24 Functionally, gamma oscillations in neuronal networks bind neurons into a common temporal regime during higher brain functions like motor behavior, sensory perception, or memory formation. 7,[25][26][27][28] The synchronizing effect of gamma oscillations permits the coordinated activation of defined sets of neurons, which constitute functional ensemblesthe putative information-carrying multicellular subsets of neuronal networks. 9,11,29 Moreover, the precise timing of action potentials is central for use-dependent synaptic plasticity and, thus, supports learning and memory formation.…”

What do we really know about newborn infant pain?

“…Electroencephalography, in contrast, is a non-invasive neurophysiological method that records the electrical activity of the brain at the scalp, largely from superficial regions, such as the somatosensory cortex, because voltage changes dissipate from deeper subcortical structures over a certain distance. It is possible to observe event-related changes in the EEG traces following certain stimuli, including noxious laser, pinprick and heel lance (Zhang et al 2012;Fabrizi et al 2013;Iannetti et al 2013). Recently, studies have identified an event-related potential in newborn infants and infants up to 1 year old, which is specific to noxious stimulation (Slater et al 2010b,c;Fabrizi et al 2011;Verriotis et al 2015).…”