Graduate School of Comprehensive Rehabilitation, Osaka Prefecture University, Habikino City, Osaka, Japan.
College of Health and Human Sciences, Osaka Prefecture University, Habikino City, Osaka, Japan.
Neuroscience. 2022 Jul 1;494:82-93. doi: 10.1016/j.neuroscience.2022.05.012. Epub 2022 May 16.
The present study examined whether tactile perception of the fingertip modulates excitability of the motor cortex supplying the intrinsic hand muscle and whether this modulation is specific to the fingertip stimulated and the muscle and hand tested. Tactile stimulation was given to one of the five fingertips in the left or right hand, and transcranial magnetic stimulation eliciting motor evoked potential in the first dorsal interosseous muscle (FDI) or abductor digiti minimi was given 200 ms after the onset of tactile stimulation. The corticospinal excitability of the FDI at rest was suppressed by the tactile stimulation of the right middle fingertip, but such suppression was absent for the other fingers stimulated and for the other muscle or hand tested. The persistence and amplitude of the F-wave was not significantly influenced by tactile stimulation of the fingertip in the right hand. These findings indicate that tactile perception of the right middle fingertip suppresses excitability of the motor cortex supplying the right FDI at rest. The suppression of corticospinal excitability was absent during tonic contraction of the right FDI, indicating that the motor execution process interrupts the tactile perception-induced suppression of motor cortical excitability supplying the right FDI. These findings are in line with a view that the tactile perception of the right middle finger induces surround inhibition of the motor cortex supplying the prime mover of the finger neighboring the stimulated finger.
本研究旨在探讨指尖触觉感知是否会调节支配内在手部肌肉的运动皮层兴奋性，以及这种调节是否具有指尖、肌肉和手部特异性。在左手或右手的五个指尖中的一个给予触觉刺激，在触觉刺激开始后 200 毫秒给予诱发第一背侧骨间肌（FDI）或小指展肌运动诱发电位的经颅磁刺激。静息时，右侧中指指尖的触觉刺激抑制 FDI 的皮质脊髓兴奋性，但对其他手指刺激和其他肌肉或手部测试没有抑制作用。F 波的持续时间和幅度不受右侧指尖触觉刺激的显著影响。这些发现表明，右侧中指指尖的触觉感知在静息时抑制支配右侧 FDI 的运动皮层兴奋性。在右侧 FDI 的紧张性收缩期间，皮质脊髓兴奋性的抑制消失，表明运动执行过程中断了对支配右侧 FDI 的运动皮层兴奋性的触觉感知诱导抑制。这些发现与一种观点一致，即右手中指的触觉感知会引起邻近刺激手指的手指的运动皮层的环绕抑制。
