Transcranial magnetic stimulation induced metaplasticity in primary somatosensory cortex

经颅磁刺激（TMS）促进神经可塑性的方法正在迅速推进我们对人类大脑功能的理解。体感觉皮层表现出tms诱导的可塑性倾向，并影响肌肉的神经控制。然而，人们对tms诱导的人体感觉皮层可塑性的机制知之甚少。控制可塑性的一种机制是元可塑性，它通过逆转神经活动的方向来限制可塑性，以保持神经回路的稳定性。理解支撑元可塑性的过程对于预测经颅磁刺激诱导的可塑性效应至关重要，对于准确研究人类大脑功能和/或促进新治疗方案的可塑性至关重要。为了准确有效地利用经颅磁刺激诱发的可塑性协议，提出的方案解决了这些问题：1)什么是元塑性的大小，方向和持续时间？2)支持元可塑性的神经机制是什么？3)在皮层和/或脊髓回路中是否发生了元可塑性效应？*******主要关注人类初级体感觉皮层，该计划将促进和表征介导可塑性和超可塑性的神经活动。该计划将独特地结合神经生理学，行为和单质子磁共振波谱（1H-MRS）的方法，以解决人类神经可塑性和元可塑性的基本问题，这些问题鲜为人知。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)揭示支配人类体感可塑性/超可塑性及其对邻近运动皮层的远程影响的规则；2)通过开发使用1H-MRS和脊髓功能磁共振成像测量脊髓内可塑性和超可塑性的方法，取得重要的技术进步；这项倡议将改变我们作为科学家研究脊柱对可塑性/超可塑性的贡献的能力，以及3)获得支持人类表现变化的神经递质浓度的详细体内测量。该计划将在感觉运动控制、神经可塑性以及经颅磁刺激在基础和临床神经科学中的应用方面产生具有深远国际影响的优秀研究成果

Transcranial magnetic stimulation (TMS) approaches to promote neural plasticity are rapidly advancing our understanding of human brain function. The somatosensory cortex demonstrates a propensity for TMS-induced plasticity and influences the neural control of muscles. However, little is known about the mechanisms that govern TMS-induced plasticity in human somatosensory cortex. One mechanism that governs plasticity is metaplasticity which acts to limit plasticity by reversing the direction of neural activity to maintain stability within neural circuits. Understanding the processes that underpin metaplasticity is of the utmost importance for predicting TMS-induced plasticity effects and is critical for accurately studying human brain function and/or promoting plasticity for novel therapeutic regimes. To accurately and effectively utilize TMS-induced plasticity protocols the proposed program addresses these questions: 1) What is the magnitude, direction and duration of metaplasticity? 2) What are the neural mechanisms that underpin metaplasticity? 3) Are metaplasticity effects occurring in the cortex and/or spinal circuitry?*******Focused on the primary somatosensory cortex in humans, the proposed program will promote and characterize neural activity that mediates plasticity and metaplasticity. The program will uniquely combine methodologies of neurophysiology, behaviour and one-proton magnetic resonance spectroscopy (1H-MRS) to address fundamental questions in human neural plasticity and metaplasticity for which little is known. This ground-breaking research will make unprecedented strides in basic neuroscience by 1) exposing the rules that govern human somatosensory plasticity/metaplasticity and its remote effects on neighbouring motor cortex, 2) making important technical advances by developing methods to measure plasticity and metaplasticity within the spinal cord using 1H-MRS and spinal functional magnetic resonance imaging, an initiative that will transform our ability as scientists to study spinal contributions to plasticity/metaplasticity, and 3) obtaining detailed in vivo measures of neurotransmitter concentration that underpin changes in human performance. The proposed program will produce excellent research with a far reaching international impact in the fields of sensorimotor control, neural plasticity and in the use of TMS in basic and clinical neuroscience.***