Integration of nociceptive information is essential to produce adapted responses, to promote body integrity and survival. However, how the brain integrates nociceptive inputs from different body areas remains unknown. The aim of this study was to examine the cortical integration of bilateral nociceptive inputs evoked by laser heat stimuli. Sixteen healthy volunteers (8 F, 8 M; age: 25.5 ± 4.3) were recruited to participate in one session during which painful laser stimuli were applied to their hands with 2 Nd:YAP laser systems. Electroencephalographic activity was recorded to measure laser-evoked potentials and event-related spectral perturbations. Twenty nociceptive stimuli were applied in each of the 4 counterbalanced conditions: (1) right hand, (2) left hand, and both hands with (3) attention to the right or (4) attention to the left. Compared with unilateral conditions, N2 and P2 peak amplitude as well as gamma oscillation power were decreased in bilateral conditions (P < 0.05), but these effects were not affected by the direction of attention (P > 0.1). By contrast, pain was not significantly different in any condition (P > 0.05). These findings show that although more nociceptive inputs reach the brain with multiple nociceptive stimuli, their sensory representation is decreased while pain perception remains unchanged. These interactions between cerebral processing of nociceptive information from different body regions could support coordinated behavioral responses when pain origins from multiple sources.
When concurrent nociceptive stimuli are applied, the amplitude of laser-evoked N2 and P2 as well as gamma oscillation power are decreased, while pain remains unchanged.
aDepartment of Chiropractic, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada
bCogNAC Research Group, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada
Corresponding author. Address: Department of Chiropractic, CogNAC Research Group, Université du Québec à Trois-Rivières, 3351 Blvd des Forges, C.P. 500, Trois-Rivières, QC G9A 5H7, Canada. Tel.: 819-376-5011; fax: 819-376-5204. E-mail address: firstname.lastname@example.org (M. Piché).
Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article.
Received August 27, 2018
Received in revised form November 05, 2018
Accepted November 20, 2018