Masakado Y, Ushiba J, Tomita Y, Chino N
Department of Rehabilitation Medicine, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582 Japan.
Electromyogr Clin Neurophysiol. 2004 Mar;44(2):83-7.
Cortical activity related to the late component of the cutanomuscular reflex was studied by measuring somatosensory evoked magnetic fields (SEFs) during isometric contraction of the reflex-induced muscle. After electrical stimulation to the index finger with intensity of three times of the perception threshold, three peaks of the cortical activity were detected within the somato-sensory area contralaterally to the stimulation site. Three dimentional location and the amplitude of the equivalent current dipoles for each peak were compared to that of observed SEF without muscle contraction. Significantly increased third component of SEFs (the latency of about 50 ms) always preceeded ca 20 ms against the peak of the late component of the cutaneomusucular reflex observed in the first dorsal interosseous (1DI) muscle. The conduction delay from the primary somatomotor cortex to the 1DI was determined as also ca 20 ms according to the result of the transcranial magnetic stimulation. We conclude from these evidences that all or part of the ingredient of the third component of SEFs may contribute to inducement of the late excitatory component of the cutaneomuscular reflex.
通过在反射诱发肌肉的等长收缩过程中测量体感诱发磁场（SEF），研究了与皮肤肌肉反射晚期成分相关的皮质活动。在用三倍于感觉阈值的强度电刺激食指后，在刺激部位对侧的体感区域内检测到了三个皮质活动峰值。将每个峰值的等效电流偶极子的三维位置和幅度与无肌肉收缩时观察到的SEF进行了比较。SEF的第三个成分（潜伏期约50毫秒）显著增加，总是比在第一背侧骨间肌（1DI）中观察到的皮肤肌肉反射晚期成分的峰值提前约20毫秒。根据经颅磁刺激的结果，从初级运动皮层到1DI的传导延迟也确定为约20毫秒。从这些证据中我们得出结论，SEF第三个成分的全部或部分成分可能有助于诱发皮肤肌肉反射的晚期兴奋性成分。
