Greater interruption of visual processing and memory encoding by visceral than somatic pain in healthy volunteers - An fMRI study.

Visceral pain is regarded as more salient than somatic pain. It has greater affective and emotional components, i.e., it elicits higher levels of pain-related fear and is perceived as more unpleasant than somatic pain. In this fMRI study, we examined the neural effects of painful visceral as compared to painful somatic stimulation on visual processing and memory encoding in a visual categorization and surprise recognition task in healthy volunteers. During the categorization task, participants received either rectal distensions or heat stimuli applied to the forearm, with stimuli being individually matched for unpleasantness. Behaviorally, visceral pain reduced memory encoding as compared to somatic pain (Kleine-Borgmann et al., 2021). Imaging analyses now revealed that visceral pain was associated with reduced activity (i.e., greater pain-related interruption) in neural areas typically involved in visual processing and memory encoding. These include the parahippocampal gyrus, fusiform gyrus, striatum, occipital cortex, insula, and the amygdala. Moreover, reduced engagement of the lateral occipital complex during visual categorization under visceral pain was associated with higher visceral pain-related fear. These findings obtained in healthy volunteers shed light on the neural circuitry underlying the interruptive effect of visceral pain and pave the way for future studies in patient samples.

Does pain modality play a role in the interruptive function of acute visceral compared with somatic pain?

ABSTRACT: Acute pain captures attentional resources and interferes with ongoing cognitive processes, including memory encoding. Despite broad clinical implications of this interruptive function of pain for the pathophysiology and treatment of chronic pain conditions, existing knowledge exclusively relies on studies using somatic pain models. Visceral pain is highly prevalent and seems to be more salient and threatening, suggesting that the interruptive function of pain may be higher in acute visceral compared with somatic pain. Implementing rectal distensions as a clinically relevant experimental model of visceral pain along with thermal cutaneous pain for the somatic modality, we herein examined the impact of pain modality on visual processing and memory performance in a visual encoding and recognition task and explored the modulatory role of pain-related fear and expectation in 30 healthy participants. Despite careful and dynamically adjusted matching of stimulus intensities to perceived pain unpleasantness over the course of trials, we observed greater impairment of cognition performance for the visceral modality with a medium effect size. Task performance was not modulated by expectations or by pain-related fear. Hence, even at matched unpleasantness levels, acute visceral pain is capable of interfering with memory encoding, and this impact seems to be relatively independent of pain-related cognitions or emotions, at least in healthy individuals. These results likely underestimate the detrimental effect of chronic pain on cognitive performance, which may be particularly pronounced in acute and chronic visceral pain.

ERP correlates of processing the auditory consequences of own versus observed actions.

Research has so far focused on neural mechanisms that allow us to predict the sensory consequences of our own actions, thus also contributing to ascribing them to ourselves as agents. Less attention has been devoted to processing the sensory consequences of observed actions ascribed to another human agent. Focusing on audition, there is consistent evidence of a reduction of the auditory N1 ERP for self- versus externally generated sounds, while ERP correlates of processing sensory consequences of observed actions are mainly unexplored. In a between-groups ERP study, we compared sounds generated by self-performed (self group) or observed (observation group) button presses with externally generated sounds, which were presented either intermixed with action-generated sounds or in a separate condition. Results revealed an overall reduction of the N1 amplitude for processing action- versus externally generated sounds in both the intermixed and the separate condition, with no difference between the groups. Further analyses, however, suggested that an N1 attenuation effect relative to the intermixed condition at frontal electrode sites might exist only for the self but not for the observation group. For both groups, we found a reduction of the P2 amplitude for processing action- versus all externally generated sounds. We discuss whether the N1 and the P2 reduction can be interpreted in terms of predictive mechanisms for both action execution and observation, and to what extent these components might reflect also the feeling of (self) agency and the judgment of agency (i.e., ascribing agency either to the self or to others).