Abstract.
Convergence of various afferent inputs onto brain-stem neurons may play an important role in the regulation of trigeminal motor function. The present study examined the efficacy of nociceptive and non-nociceptive perioral stimulation for the modulation of the two exteroceptive suppression periods (ES1 and ES2) in human jaw-closing muscles. The inhibitory jaw-reflexes, ES1 (10–15 ms onset) and ES2 (40–50 ms onset), were recorded as the surface electromyogram of masseter and temporalis muscles in 14 healthy subjects. Non-painful electrical stimuli were applied to the right mental nerve while the subject was biting at 50% of the maximal voluntary force. Five conditions were compared: baseline, repetitive tactile stimulation (1 Hz) on the right cheek, topical application of capsaicin (5%) on the right cheek, repetitive tactile stimulation plus capsaicin, and post-baseline. The perceived intensity of the electrical stimuli was evaluated by the subjects on a 0–10 rating scale. Capsaicin alone failed to induce significant changes of ES1 and ES2; tactile stimulation alone induced a significant delay in the onset of ES2 (P<0.001). During repetitive tactile stimulation plus capsaicin, the duration of ES1 and ES2 was shortened (ES1 and ES2: P<0.001) and the degree of suppression was reduced (ES1: P<0.05; ES2: P<0.005). Perceived intensity of the electrical stimuli was unchanged during the different experimental conditions. The present results suggest that summation of simultaneous nociceptive and non-nociceptive inputs plays an important role in the modulation of the neural pathways involved in the short-latency ES1 and long-latency ES2.
Similar content being viewed by others
Author information
Authors and Affiliations
Additional information
Electronic Publication
Rights and permissions
About this article
Cite this article
Romaniello, A., Svensson, P., Cruccu, G. et al. Modulation of exteroceptive suppression periods in human jaw-closing muscles induced by summation of nociceptive and non-nociceptive inputs. Exp Brain Res 132, 306–313 (2000). https://doi.org/10.1007/s002210000353
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s002210000353