Sonnenborg F A, Andersen O K, Arendt-Nielsen L, Treede R D
Laboratory for Experimental Pain Research, Center for Sensory-Motor Interaction, Aalborg University, Denmark.
Exp Brain Res. 2001 Feb;136(3):303-12. doi: 10.1007/s002210000587.
The present study investigated excitatory reflex receptive fields for various muscle reflex responses and reflex mediated ankle joint movements using randomised electrical stimulation of the dorsal and plantar surface of the foot in 12 healthy subjects. Eleven electrodes (0.5-cm2 cathodes) were mounted on the dorsal side and three on the plantar side of the foot. A low (1.5 times pain threshold) and a high (2.3 times pain threshold) stimulus intensity were used to elicit the reflexes. EMG signals were recorded from tibialis anterior (TA), gastrocnemius medialis (GM), soleus (SO), biceps femoris (BF), and rectus femoris (RF) muscles together with the ankle movement measured by a goniometer. The withdrawal pattern evoked from the dorsal side consisted of two separate responses with different receptive fields: (1) early EMG responses in GM and BF (50-120 ms) evoking knee flexion, probably of purely spinal origin, and (2) a late response in GM and SO (120-200 ms) that may be under supraspinal control. The ankle flexor TA was significantly activated in both time windows, but in 11 of 12 subjects its contraction was too small to cause significant dorsal flexion. In the ankle joint inversion was the most dominant movement. Stimulation of the plantar side resulted in activation of TA when stimulating the forefoot and in activation of triceps surae when stimulating the heel. These observations show that painful stimuli activate appropriate muscles depending on stimulus location to initiate the adequate withdrawal. For proximal muscles (e.g. knee flexors) the receptive field covers almost the entire foot (dorsal and plantar sides) while more distal muscles have a smaller receptive field covering only a part of the foot. This adequate withdrawal movement suggests a more refined withdrawal reflex organisation than a stereotyped flexion of all joints to avoid tissue damage.
本研究通过对12名健康受试者的足背和足底进行随机电刺激，研究了各种肌肉反射反应和反射介导的踝关节运动的兴奋性反射感受野。11个电极（0.5平方厘米的阴极）安装在足背侧，3个安装在足底侧。使用低（疼痛阈值的1.5倍）和高（疼痛阈值的2.3倍）刺激强度来引发反射。从胫骨前肌（TA）、腓肠肌内侧头（GM）、比目鱼肌（SO）、股二头肌（BF）和股直肌（RF）记录肌电图信号，并通过角度计测量踝关节运动。从背侧诱发的退缩模式由两个具有不同感受野的独立反应组成：（1）GM和BF中早期肌电图反应（50 - 120毫秒），引发膝关节屈曲，可能纯粹起源于脊髓，（2）GM和SO中的晚期反应（120 - 200毫秒），可能受脊髓上控制。踝关节屈肌TA在两个时间窗口均显著激活，但在12名受试者中的11名中，其收缩太小，不足以引起明显的背屈。在踝关节，内翻是最主要的运动。刺激足底侧在刺激前足时导致TA激活，在刺激足跟时导致小腿三头肌激活。这些观察结果表明，疼痛刺激根据刺激位置激活适当的肌肉，以启动适当的退缩。对于近端肌肉（如膝关节屈肌），感受野几乎覆盖整个足部（背侧和足底侧），而更远端的肌肉感受野较小，仅覆盖足部的一部分。这种适当的退缩运动表明，与所有关节的刻板屈曲相比，退缩反射组织更为精细，以避免组织损伤。
