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。躯体感觉皮层表现出TMS诱导可塑性的倾向，并影响肌肉的神经控制。然而，对TMS诱导的人体体感皮质可塑性的调控机制却知之甚少。控制可塑性的一个重要机制是元可塑性，它通过逆转神经活动的方向来限制可塑性，以维持神经回路内的稳定。了解支持可塑性的过程对于预测TMS诱导的可塑性效应是至关重要的，并且对于准确研究人脑功能和/或促进新的治疗方案的可塑性至关重要。为了准确和有效地利用TMS诱导的可塑性方案，建议的程序解决了以下问题：1)元可塑性的大小、方向和持续时间是什么？2)支持可塑性的神经机制是什么？3)在大脑皮层和/或脊髓回路中是否发生了可塑性效应？*专注于人类的初级躯体感觉皮质，建议的程序将促进和表征调节可塑性和可塑性的神经活动。该计划将独特地结合神经生理学、行为学和单质子磁共振波谱(1H-MRS)的方法，解决人类神经可塑性和化塑性中鲜为人知的基本问题。这项开创性的研究将通过以下方式在基础神经科学领域取得前所未有的进展：1)揭示人类躯体感觉可塑性/可塑性及其对邻近运动皮质的远程影响的规则；2)通过开发使用1H-MRS和脊髓功能磁共振成像来测量脊髓内可塑性和可塑性的方法，取得重要的技术进步，这一举措将改变我们作为科学家研究脊髓对可塑性/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。拟议的计划将在感觉运动控制、神经可塑性以及TMS在基础和临床神经科学中的使用领域产生具有深远国际影响的优秀研究。*

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.***