Mechanisms of interhemispheric inhibitionin human motor cortex

促进运动皮质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于人们渴望了解大脑和脊髓是如何控制运动的，并最终为治疗方法的发展提供信息。在运动皮质中有肌肉的代表，这些代表所占据的空间或领土根据任务的背景而变化。例如，当发生移动时，表示法会展开。然而，人们对控制人类运动皮质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大脑半球间抑制。这是一种神经机制，其中一个半球的运动皮质抑制另一个半球的运动皮质的活动。我们先前的研究表明，大脑半球间抑制的强度与运动皮质内肌肉表征的大小有关。这是一个重要的发现，因为如果大脑半球间抑制控制运动皮质组织的某些特性，我们可能能够操纵大脑半球间抑制作为改变运动皮质内组织的一种方法。为了准确和有效地利用大脑半球间抑制，该计划解决了以下问题：1)哪些神经递质受体介导大脑半球间抑制？2)大脑半球抑制的大小是否与运动皮质内肌肉表征的大小有关？3)能否通过操纵大脑半球间抑制来引起运动皮质内肌肉表征的相应变化？该计划的重点是人类的初级运动皮质，该计划将描述一种神经机制，该机制被预测为控制运动皮质的活动。该计划将独特地结合神经生理学、药理学、功能近红外光谱学和单质子磁共振光谱学(1H-MRS)的方法来解决人类运动皮质的基本问题。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展：1)确定调节大脑半球间抑制的抑制性神经递质受体，2)确定调节大脑半球间抑制的新机会，3)确定改变人类运动皮质组织的新机会。

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.