Department of Psychology, University of California San Diego, La Jolla, San Diego, USA.
Exp Brain Res. 2020 Aug;238(7-8):1637-1644. doi: 10.1007/s00221-020-05803-0. Epub 2020 Apr 18.
Transcranial magnetic stimulation (TMS) is one of the most popular non-invasive tools for investigating the cortical circuits involved in human movement. Stimulation of the primary motor cortex elicits motor evoked potentials in peripheral muscles, the amplitude of which reflects the net excitability of circuits in the cortex and spinal cord. A number of methods exist to help broadly distinguish between excitatory and inhibitory influences on corticospinal output, allowing us to probe changes in the respective cortical circuits before and during movement. Something that has rarely been considered in human TMS studies, however, is the idea that specific populations of excitatory neurons might underlie different aspects of motor behavior. The current article provides a brief review of recent TMS studies which suggest that it is possible to selectively probe distinct excitatory inputs to corticospinal neurons during a range of movement-related states, from the preparation and execution of movements, to the suppression of unwanted movements. Together with recent advancements in computational modelling of the mechanisms of TMS and the capacity to record single-cell responses to TMS in behaving non-human primates, this avenue of research has the potential to shed light on the motor circuits underlying the repertoire of human motor behaviors, as well as their pathophysiology in diseases of the motor system.
经颅磁刺激（TMS）是一种非常流行的非侵入性工具，可用于研究涉及人类运动的皮质电路。刺激初级运动皮层会在外周肌肉中引发运动诱发电位，其幅度反映了皮质和脊髓中电路的净兴奋性。有许多方法可以帮助我们大致区分对皮质脊髓输出的兴奋性和抑制性影响，从而在运动前后探测到相应皮质电路的变化。然而，在人类 TMS 研究中很少考虑到的一个问题是，特定的兴奋性神经元群体可能是运动行为不同方面的基础。本文简要回顾了最近的 TMS 研究，这些研究表明，在一系列与运动相关的状态下，从运动的准备和执行到对不想要的运动的抑制，有可能选择性地探测到皮质脊髓神经元的不同兴奋性输入。结合 TMS 机制的计算建模的最新进展以及在行为灵长类动物中记录 TMS 对单个细胞反应的能力，这一研究方向有可能揭示人类运动行为背后的运动电路，以及运动系统疾病中的病理生理学。
