Department of Cognitive Behavioral Physiology, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chuouku, Chiba 260-8670, Japan.
Exp Brain Res. 2012 Jan;216(1):135-44. doi: 10.1007/s00221-011-2917-3. Epub 2011 Nov 11.
Voluntary contraction of a muscle generates electromyographic (EMG) activity in the homologous muscle on the opposite side (mirror-like activity), not only in pathological states and in infants but also in healthy adults. Few studies have examined whether the cutaneous reflexes during the preparatory period of a reaction time task are affected by mirror-like activity. In the present study, we investigated the modulation of the cutaneous reflexes in the left first interosseous (FDI) muscle in 9 healthy subjects while they performed a quick abduction of the right index finger during a reaction time task. Cutaneous reflexes were elicited by applying non-noxious electrical stimulation to the left index finger. We found that mirror-like activity occurred in the left FDI at approximately the onset of EMG activity in the right FDI. The excitatory E2 component was selectively increased at 75 ms after the "Go" signal, which corresponded to the onset of mirror-like activity. The inhibitory I2 (90 ms) component was tuned consistently into excitation after the "Go" signal. These findings suggest that long latency reflexes, possibly transcortical cutaneous reflexes, are finely tuned in relation to mirror-like activity.
肌肉的随意收缩会在对侧（镜像活动）同一块肌肉中产生肌电图（EMG）活动，不仅在病理状态和婴儿中如此，在健康成年人中也是如此。很少有研究探讨在反应时间任务的预备期期间，皮肤反射是否会受到镜像活动的影响。在本研究中，我们在 9 名健康受试者进行反应时间任务时快速外展右手食指的过程中，研究了左第一骨间（FDI）肌皮肤反射的调制。通过对左食指施加非伤害性电刺激来引发皮肤反射。我们发现，镜像活动大约在右 FDI 的 EMG 活动开始时出现在左 FDI 中。兴奋性 E2 成分在“Go”信号后约 75 毫秒选择性增加，这与镜像活动的开始相对应。抑制性 I2（约 90 毫秒）成分在“Go”信号后始终调整为兴奋。这些发现表明，长潜伏期反射（可能是皮质下皮肤反射）与镜像活动精细调节。
