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

当今的主要科学问题之一涉及人类大脑的功能。减缓科学进步的一个重要问题是，在人类身上能否找到适当的方法，这些方法可以提供类似于在动物和体外实验中可能得到的详细的机制答案。在运动神经科学中，存在一种称为经颅磁刺激h反射条件反射（TMS）的神经生理学技术，可以研究人体皮质脊髓系统。通过这种方法，突触的活性和可塑性已经被探测到皮质脊髓连接的一个特定子集，即最快的（大直径）单突触皮质脊髓（锥体）通路，这被认为只存在于旧大陆灵长类动物和人类中。最近关于h反射条件作用的研究进展表明，不仅可以探测到最快的传导皮质脊髓（锥体）投射，也可以探测到起源于初级运动皮层（M1）的传导较慢的传导皮质脊髓（锥体）投射。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，它将测试在多大程度上其他投射源自运动前区域可以测试h反射条件。最后，现有的研究皮质-皮质和皮质-脊髓投射的神经生理学方法（短间隔皮质内抑制- SICI；皮质内促进- ICF；经颅磁刺激前运动-运动调节）将与h反射调节技术相结合。与现有方法的结合以及研究M1较慢的锥体投射的可能性可能会导致新的神经生理学工具，在未来可以更好地研究人类的皮质脊髓系统。

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.