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.

中文翻译：

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经颅磁刺激：进入与人类运动行为有关的兴奋回路的非侵入性窗口。

经颅磁刺激（TMS）是研究人体运动中涉及的皮层回路的最流行的非侵入性工具之一。初级运动皮层的刺激会引起周围肌肉的运动诱发电位，其振幅反映了皮层和脊髓中回路的净兴奋性。存在许多方法可以广泛地区分对皮质脊髓输出的兴奋性和抑制性影响，从而使我们能够探究运动之前和运动过程中各个皮质回路的变化。然而，在人类TMS研究中很少考虑的事情是，特定的兴奋性神经元群体可能是运动行为的不同方面的基础。当前文章简要回顾了最新的TMS研究，这些研究表明，在一系列与运动有关的状态（从运动的准备和执行到抑制不必要的运动）中，有可能选择性地探测皮质神经元的不同兴奋性输入。加上TMS机制的计算机建模的最新进展以及记录非人类灵长类动物行为的TMS单细胞反应的能力，这种研究途径有可能揭示人类运动的基础行为，及其在运动系统疾病中的病理生理学。抑制不必要的动作。加上TMS机制的计算模型的最新进展以及记录非人类灵长类动物行为对TMS的单细胞应答的能力，这种研究途径有可能揭示人类运动基础中的运动电路行为，及其在运动系统疾病中的病理生理学。抑制不必要的动作。加上TMS机制的计算模型的最新进展以及记录非人类灵长类动物行为对TMS的单细胞应答的能力，这种研究途径有可能揭示人类运动基础中的运动电路行为，及其在运动系统疾病中的病理生理学。