Anticipatory cortical responses during the expectancy of a predictable painful stimulation. A high‐resolution electroencephalography study

Abstract

In the present study, high-resolution electroencephalography techniques modelled the spatiotemporal pattern of human anticipatory cortical responses preceding expected galvanic painful stimuli (non-painful stimuli as a control). Do these responses reflect the activation of associative other than somatosensory systems? Anticipatory processes were probed by alpha oscillations (6-12 Hz) for the evaluation of thalamocortical channels and by negative event-related potentials for the evaluation of cortical excitability. Compared with the control condition, a progressive reduction of the alpha power was recognized over the primary somatosensory cortex from 2 s before the painful stimulation. In contrast, the anticipatory event-related potentials were negligible during the expectancy period. The results on the alpha power suggest that the expectancy of the painful stimulation specifically facilitated the somatosensory thalamocortical channel. Remarkably, the associative frontal-parietal areas were not involved, possibly due to the predictable and repetitive features of the painful stimulus. The present results also suggest that negative event-related potentials are modest preceding warned stimuli (even if painful) with a simple information content.

Prestimulus Oscillatory Activity in the Alpha Band Predicts Visual Discrimination Ability

“…Previous studies on prestimulus alpha activity and detection ability have yielded inconsistent results (Babiloni et al, 2003;Ergenoglu et al, 2004). One explanation for the discrepancies might stem from the fact that several sources in the human brain produce oscillatory activity in the alpha band (Hari and Salmelin, 1997).…”

Pre- and post-stimulus alpha activity shows differential modulation with spatial attention during the processing of pain

“…Both studies, however, did not investigate possible pre-stimulus effects of attention. Previous work addressing pre-stimulus effects showed that anticipation of a painful stimulus already results in a suppression of alpha activity (Babiloni et al, 2003(Babiloni et al, , 2004Del Percio et al, 2006). This anticipatory suppression is again stronger for a painful compared to a non-painful stimulus (Babiloni et al, 2003) and less prominent, if the subject is distracted by mentally performing an arithmetical task .…”

Linear and nonlinear analyses of EEG dynamics during non-painful somatosensory processing in chronic pain patients

“…Thus, for instance, lowered power in the alpha rhythm over primary somatosensory cortex has been observed during the expectancy of predictable painful stimulation (Babiloni et al, 2003(Babiloni et al, , 2006. Early reports have also revealed that chronic pain patients show less alpha asymmetry than healthy subjects (De Benedittis and De Gonda, 1985;Stevens et al, 2000), and that neurofeedback training to increase alpha waves would be an effective method to reduce pain perception (Melzack and Perry, 1975).…”