Tonic pain reduces autonomic responses and EEG functional connectivity elicited by affective stimuli

Abstract

Most pain studies have focused on only two aspects of pain: the influence of pain on attentional processing and the modulation of pain perception by affective stimuli. However, the influence of tonic pain on the attentional processing of affective stimuli has not been studied. In this study, we investigated the effects of tonic pain on the attentional processing of affective stimuli, focusing on autonomic responses and their relationship with both EEG power and functional connectivity. Forty participants (20 men and 20 women) received tonically painful and nonpainful thermal stimulation while viewing blocks of pleasant, unpleasant, or neutral images. The galvanic skin conductance response (SCR), electrocardiographic activity, and electroencephalographic (EEG) activity in the delta and theta bands were recorded. Participants rated the unpleasantness of the pain at the end of each block. Typical affective SCR and heart rate (HR) patterns were found in the no‐pain condition, but when the pain was delivered, these patterns disappeared. EEG power and functional connectivity results showed that tonic pain affected the delta band in the central region during pleasant and unpleasant image blocks. Our findings suggest that tonic pain captured attentional focus and reduced the cognitive resources available for processing affective stimuli, altering the emotional experience associated with pain.

Healthy ageing and cognitive impairment alter EEG functional connectivity in distinct frequency bands

“…FC can be studied at various spatial and temporal scales, using brain signals such as functional magnetic resonance imaging (fMRI), electro/magneto‐encephalogram (EEG/MEG) or neuronal firing activity, and is quantified using a variety of techniques such as coherence (Srinivasan et al, 2007), imaginary part of coherence (Nolte et al, 2004), phase locking value (PLV; [Lachaux et al, 2000]), pairwise phase consistency (PPC; [Vinck et al, 2010]) and so on. Many studies have reported changes in FC in different frequency bands with cognitive tasks such as working memory visual discrimination (Lachaux et al, 1998), emotional face processing (Li et al, 2015), fixation tasks (Murty et al, 2018), pain perception tasks (Alba et al, 2022), motor learning tasks (Heitger et al, 2012), ageing and with brain disorders (Ishii et al, 2017). For example, reduction in alpha (8–12 Hz) FC was reported with healthy ageing in resting state EEG (Moezzi et al, 2019), whereas gamma (30–55 Hz) FC reduction was reported in autism (Safar et al, 2020) and in Alzheimer's disease (AD) and schizophrenia (Uhlhaas & Singer, 2006).…”