Investigating the effects of visual-nociceptive interaction on corticospinal excitability in augmented reality

Details

Supervisors

Filbrich, Lieve

Faculty

Faculté de psychologie, logopédie, sexologie et des sciences de la famille

Degree label

Master [120] en sciences psychologiques, à finalité spécialisée

Abstract

enPain is viewed as a multisensory, action-oriented process supporting adaptive behavior. Nociceptive sensitization can alter the processing of sensory events associated with the sensitized body part, while both approaching visual stimuli and capsaicin-induced sensitization may modulate corticospinal excitability (CSE). However, whether these effects interact remains unclear. The present study investigated this question. Seventy-two healthy adults were assigned to a capsaicin or control group. The capsaicin group received topical 1% capsaicin on one forearm and vehicle on the other, while controls received vehicle on both arms. CSE was assessed through motor-evoked potentials elicited by single-pulse TMS and recorded from the FDI, while a realistic virtual wasp in augmented reality either approached the target arm (the capsaicin-treated arm in the capsaicin group), the contralateral non-target arm, or remained at a distance from the body (baseline condition). Subjective ratings, sensory measures and skin temperature measures were collected. Results showed that baseline MEP amplitude increased from pre- to post-sensitization similarly in both groups. Moreover, approaching threats did not generally modulate CSE across participants. Crucially, in the capsaicin group, MEP amplitudes were significantly reduced when the wasp approached the sensitized target arm, compared with both the post-manipulation baseline and the non-target arm condition, whereas no comparable modulation was observed in the control group. These findings suggest that the current nociceptive state may influence motor responses to an approaching visual threat according to the behavioral relevance of the threatened body part. Future studies should further characterize these interactions by controlling the sensory components and perceived threat of approaching stimuli and determine whether similar effects occur in clinical pain populations. Key references: Farina et al. (2001); Legrain et al. (2011); Makin et al. (2009) ; Torta et al. (2017) ; van den Broeke & Mouraux (2014).