Mechanisms of interhemispheric inhibitionin human motor cortex

促进运动皮层内的神经可塑性是人类神经科学的一个重要研究热点。这种科学兴趣在很大程度上是由理解大脑和脊髓如何控制运动的愿望所驱动的，并最终为治疗方法的发展提供信息。在运动皮层中有肌肉的表征，这些表征所占据的空间或区域根据任务的背景而变化。例如，当运动发生时，表征会扩展。然而，人们对控制人类运动皮层内肌肉表征变化的机制知之甚少。一种可能起作用的机制被称为半球间抑制。这是一种神经机制，其中一个半球的运动皮层抑制另一个半球的运动皮层的活动。我们之前的研究表明，半球间抑制的强度与运动皮层内肌肉表征的大小有关。这是一个重要的发现，因为如果半球间抑制控制着运动皮层组织的某些特性，我们可能能够操纵半球间抑制作为改变运动皮层组织的一种方法。为了准确和有效地利用半球间抑制，提出的方案解决了以下问题：1)什么神经递质受体介导半球间抑制？2)半球间抑制的大小是否与运动皮层内肌肉表征的大小有关？3)半球间抑制是否可以被操纵，从而在运动皮层内的肌肉表征中产生伴随的变化？重点是人类的初级运动皮层，该计划将描述一种预测控制运动皮层活动的神经机制。该项目将独特地结合神经生理学、药理学、功能近红外光谱和单质子磁共振光谱（1H-MRS）的方法来解决人类运动皮层的基本问题。这项开创性的研究将在基础神经科学领域取得前所未有的进步：1)确定介导半球间抑制的抑制性神经递质受体，2)确定调节半球间抑制的新机会，以及3)确定修改人类运动皮层组织的新机会。

Promoting neural plasticity within motor cortex is a key research focus in human neuroscience. This scientific interest is largely driven by the desire to understand how the brain and spinal cord control movement and to ultimately inform the development of therapeutic approaches. Within the motor cortex there are representations of muscles, and the space or territory occupied by these representations change depending on the context of the task. For example, when movement occurs, representations expand. However, little is known about the mechanisms that govern changes in the muscle representations within human motor cortex. One mechanism likely to contribute is called interhemispheric inhibition. This is a neural mechanism whereby the motor cortex in one hemisphere inhibits the activity of the motor cortex in the opposite hemisphere. Our previous research has shown that the strength of interhemispheric inhibition relates to the size of the muscle representation within motor cortex. This is an important finding because, if interhemispheric inhibition governs some properties of motor cortex organization, we may be able to manipulate interhemispheric inhibition as a method to alter the organization within motor cortex. To accurately and effectively utilize interhemispheric inhibition the proposed program addresses these questions: 1) What neurotransmitter receptors mediate interhemispheric inhibition? 2) Does the magnitude of interhemispheric inhibition relate to the size of the muscle representation within motor cortex? 3) Can interhemispheric inhibition be manipulated to create concomitant changes in the muscle representations within motor cortex? Focused on the primary motor cortex in humans, the proposed program will characterize a neural mechanism that is predicted to govern activity in motor cortex. The program will uniquely combine methodologies of neurophysiology, pharmacology, functional near-infrared spectroscopy, and one-proton magnetic resonance spectroscopy (1H-MRS) to address fundamental questions in human motor cortex. This ground-breaking research will make unprecedented strides in basic neuroscience by 1) identifying the inhibitory neurotransmitter receptors that mediate interhemispheric inhibition, 2) identifying new opportunities to modulate interhemispheric inhibition, and 3) identifying new opportunities to modify the organization of human motor cortex.