Madeleine Pascal, Leclerc Fredéric, Arendt-Nielsen Lars, Ravier Philippe, Farina Dario
Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7D-3, 9220 Aalborg East, Denmark.
Clin Neurophysiol. 2006 Nov;117(11):2436-45. doi: 10.1016/j.clinph.2006.06.753. Epub 2006 Sep 22.
To investigate the effect of local excitation of nociceptive muscle afferents on the spatial distribution of muscle activity.
Surface electromyographic (EMG) signals were recorded from the upper trapezius muscle of 10 healthy volunteers with a 5 x 13 electrode grid during 90-s isometric contractions before, during, 15 and 30 min after intramuscular injection of hypertonic (painful) or isotonic (non-painful) saline. From the multi-channel EMG recordings, two-dimensional maps of root mean square and mean power frequency were obtained. The centre of gravity of the root mean square map was used to quantify global changes in the spatial distribution of muscle activity.
During sustained contractions, average root mean square increased, average mean frequency decreased and the centre of gravity moved cranially. During experimental muscle pain, compared to before injection, the average root mean square decreased and there was a caudal shift of the centre of gravity. Fifteen minutes after the painful injection the centre of gravity returned to its original position.
Short-term dynamic reorganization of the spatial distribution of muscle activity occurred in response to nociceptive afferent input.
The study furnishes an extension of the pain adaptation model indicating heterogeneous inhibition of muscle activity.
研究伤害性肌肉传入神经的局部兴奋对肌肉活动空间分布的影响。
在10名健康志愿者的斜方肌上，使用5×13电极网格记录表面肌电图（EMG）信号，记录时间为肌肉注射高渗（疼痛）或等渗（非疼痛）盐水前、注射过程中、注射后15分钟和30分钟的90秒等长收缩过程。从多通道EMG记录中，获得均方根和平均功率频率的二维图。均方根图的重心用于量化肌肉活动空间分布的整体变化。
在持续收缩期间，平均均方根增加，平均频率降低，重心向头侧移动。在实验性肌肉疼痛期间，与注射前相比，平均均方根降低，重心向尾侧移动。疼痛注射后15分钟，重心恢复到原来位置。
伤害性传入神经输入导致肌肉活动空间分布发生短期动态重组。
该研究扩展了疼痛适应模型，表明对肌肉活动存在异质性抑制。
