Movements modulate cortical activities evoked by noxious stimulation

Abstract

To evaluate the effects of movement on cortical activities evoked by noxious stimulation, we recorded magnetoencephalography following noxious YAG laser stimulation applied to the dorsum of the left hand in normal volunteers. Results of the present study can be summarized as follows: (1) active movement of the hand ipsilateral to the side of noxious stimulation resulted in significant attenuation of both primary and secondary somatosensory cortices (SI and SII) in the hemisphere contralateral to the stimulated hand (cSI and cSII). Activity in the hemisphere ipsilateral to the side of stimulation (iSII) was not affected. (2) Active movement of the hand contralateral to the side of noxious stimulation resulted in significant attenuation of cSII. Activity in cSI and iSII was not affected. (3) Passive movement of the hand ipsilateral to the side of noxious stimulation resulted in significant attenuation of cSI. Activity in cSII and iSII was not affected. (4) Visual analogue scale (VAS) changes showed a similar pattern to the amplitude changes of cSII. These results suggest that activities in three regions are modulated by movements differently. Inhibition in cSI was considered to be mainly due to an interaction in SI by the signals ascending from the stimulated and movement hand. Inhibition in cSII was considered to be mainly due to particular brain activities relating to motor execution and/or movement execution associated with a specific attention effect. In addition, since VAS changes showed a similar relationship with the amplitude changes of cSII, cSII may play a role in pain perception.

Cortical Activation Changes during Repeated Laser Stimulation: A Magnetoencephalographic Study

“…Since the number of stimuli lost due to the subjects' interceptions was comparatively small (55 out of 660 stimuli, 8.3%), no special analysis was performed in regard to the trials followed by movement. However, as finger movements [18] and muscle contractions [19] attenuate pain-related cortical responses, all responses acquired after such movement were discarded from the analysis.…”

Pain-related evoked potentials are modulated across the cardiac cycle

“…The onset latency of cortical activity in SI and SII, the proposed site of interaction, following noxious YAG laser stimulation to the hand has been recorded at 90-110 ms (Nakata et al, 2004;Wang et al, 2007). Thus, as N2-P2 was modulated from 200 ms after the R-wave, the earliest time the SII must be affected by baroreceptor activity is 290 ms after the R-wave.…”

Somatosensory Processing of the Tongue in Humans

“…Compared with SI, SII has been speculated to serve a higher level of cognitive function in somatosensory processing, such as attention, decision-making, object recognition, and the integration of nociceptive and non-nociceptive inputs (Mima et al, 1998; Steinmetz et al, 2000; Romo et al, 2002; Torquati et al, 2003; Inui et al, 2004; Nakata et al, 2004; Wasaka et al, 2005). The notion that SII is higher than SI in hierarchy was proposed on the basis of their anatomical relationships: SI sends projections to SII, while SII projects back to the superficial layers of SI (see a review, Iwamura, 1998).…”