H-reflex conditioning with TMS: An important electrophysiological tool in motor neuroscience?!

今天的主要科学问题之一是关于人类大脑的功能。减缓科学进步的一个重要问题是，在人类中是否有适当的方法可以提供类似于动物和体外实验中可能提供的详细机制答案。在运动神经科学中，存在一种称为经颅磁刺激（TMS）的H反射条件反射的神经生理学技术，可以研究人类皮质脊髓系统。用这种方法，突触活动和可塑性已被探测到的一个特定子集的皮质脊髓连接，即最快的（大直径）单突触皮质脊髓（锥体）通路，已被提出只存在于旧世界灵长类动物和人类。最近的进展与H反射条件反射表明，不仅最快的，但也慢进行皮质脊髓（锥体）的投射起源于初级运动皮层（M1）可能会被探测。本项目旨在评估这在多大程度上是可能的。此外，在该项目中，将测试起源于运动前区的其他投射在多大程度上可以通过H反射条件反射进行测试。最后，研究皮质-皮质和皮质-脊髓投射的现有神经生理学方法（短间隔皮质内抑制- SICI;皮质内易化- ICF;使用TMS的前运动-运动条件反射）将与H反射条件反射技术相结合。与现有的方法和可能性相结合，研究也较慢的锥体投射从M1可能会导致新的神经生理学工具，在人类的皮质脊髓系统可以更好地研究在未来。

One of the major scientific questions today concerns the functioning of the human brain. A significant problem that slows down scientific progress is the availability of appropriate methods in humans that can provide detailed mechanistic answers similar to what is possible in animal and in in-vitro experiments. In motor neuroscience, a neurophysiological technique called H-reflex conditioning with transcranial magnetic stimulation (TMS) exists, with which the human corticospinal system can be investigated. With this method, synaptic activity and plasticity have been probed for a specific subset of corticospinal connections, namely the fastest (large diameter) monosynaptic corticospinal (pyramidal) pathways, which have been proposed to be only present in old world primates and humans. Recent advances with H-reflex conditioning suggest that not only the fastest but also slower conducting corticospinal (pyramidal) projections originating in the primary motor cortex (M1) may be probed. The present project aims to assess to which extent this is possible. Further, in the project it will be tested to which extent other projections originating in premotor areas can be tested by H-reflex conditioning. Finally, existing neurophysiological methods to study cortico-cortical and cortico-spinal projections (short-interval intracortical inhibition - SICI; intracortical facilitation - ICF; premotor-motor conditioning with TMS) will be combined with the H-reflex conditioning technique. The combination with existing methods and the possibility to study also slower pyramidal projections from M1 may lead to new neurophysiological tools with which the corticospinal system in humans can be better investigated in the future.