Resolving functions of neurons and connections of the human corticospinal system

控制运动的神经系统的一个重要部分是运动皮质和脊髓，它们通过皮质脊髓通路和不同的脑干通路相连。传统上，运动皮质被认为是一个中继站，将大脑水平产生的信息传递到脊髓和骨骼肌。然而，近年来研究运动皮质错综复杂的回路和与脊髓的联系的研究积累的证据表明，这些结构对各种功能至关重要，从协调动作的控制到动作抑制，再到决策和学习。目前的项目包含了一些最新的发展，目的是从人类神经系统的角度推进这方面的知识。因此，我们将应用一种由经颅磁刺激(TMS)和脊髓H反射相结合的无创电生理技术。该方法允许探测皮质脊髓系统三个不同水平的神经活动变化，即：i)皮质脊髓向脊髓运动神经元传递的变化，ii)运动皮质中皮质脊髓输出神经元活动的变化，以及iii)运动皮质更复杂回路的活动变化。有计划的研究的中心假设是，这三个组成部分将在控制灵活运动、运动决策和运动学习中发挥不同的作用，因此将显示与灵巧性、决策和运动学习相关的选择性活动调节。我们的研究的预期结果旨在提高目前对被测试组件在人体运动控制中的功能的理解。

An important part of the nervous system for movement control is the motor cortex and the spinal cord, which are connected via the corticospinal pathway and also via different brainstem pathways. Classically, motor cortex was considered as a relay station, forwarding information that is produced at the level of the brain to the spinal cord and to the skeletal muscles. However, accumulating evidence over recent years from studies investigating the intricate circuits of motor cortex and connections to the spinal cord suggest that these structures are crucial for a variety of features, ranging from the control of coordinated actions, to action inhibition, to decision making and to learning. The current project takes up some of the recent developments and aims to advance this knowledge with view to the human nervous system. Therefore, we will apply a non-invasive electrophysiological technique consisting of transcranial magnetic stimulation (TMS) combined with spinal H-reflexes. The method allows to probe neural activity changes at three different levels of the corticospinal system, namely: i) changes in corticospinal transmission to spinal motoneurones, ii) changes in activity of corticospinal output neurons in motor cortex, and iii) changes in activity of more complex circuits of motor cortex. The central hypothesis of the planned investigations is that these three components will have different roles in controlling dexterous movements, in motor decision making, and in motor learning, and thus will show selective activity modulations that relate to dexterity, aspects of decision making and motor learning. The expected results from our investigations aim to improve the current understanding of the function of the tested components in human movement control.