The dynamics of cortical GABA in human motor learning.
The dynamics of cortical GABA in human motor learning.
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DOI：
10.1113/jp276626
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发表时间：
2019-01
期刊：
影响因子：
--
通讯作者：
Stagg CJ
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文献类型：
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作者：
Kolasinski J;Hinson EL;Divanbeighi Zand AP;Rizov A;Emir UE;Stagg CJ
学习新运动技能的能力得到了人脑初级运动皮质结构和功能组织的可塑性的支持。GABA对信号的抑制变化被认为是诱导运动皮质可塑性的关键。本研究利用磁共振波谱(MRS)对运动学习期间、运动期间和静止期间人类运动皮质中的GABA浓度进行了量化。我们报告了MRS测量的特定于学习的GABA浓度降低的证据。此外，学习任务早期的GABA浓度与随后学习的程度密切相关：较高的GABA浓度与较差的学习有关。这些结果初步揭示了与运动学习相关的皮质可塑性的神经化学相关性，特别是在中风康复期间诱导皮质可塑性的治疗努力中。学习新奇运动技能的能力是我们日常生活的核心部分，可以为中风后的康复提供一个模式。然而，在我们对支撑人类运动可塑性的生理机制的理解上仍然存在根本的差距。新运动技能的获得依赖于初级运动皮质(M1)局部回路的变化。这种重组被认为是通过调节神经递质GABA减少局部抑制来促进的，但这种联系尚未在人类身上得到确凿的证明。在这里，我们使用7℃磁共振波谱来研究在学习一个明确的、连续的反应时间任务期间，人类M1中GABA浓度的动态变化。我们观察到，在运动学习过程中，GABA浓度显著降低，这在缺乏可学习顺序的同等运动任务中是看不到的，在相同持续时间的被动休息任务中也看不到。各组谷氨酸水平均未见明显变化。此外，在任务表现早期测量的M1 GABA与后续学习的程度密切相关，因此，较大的抑制与较差的后续学习相关。这一结果表明，较高水平的皮质抑制可能存在一种障碍，必须克服该障碍才能提高M1的兴奋性，从而编码一种新的运动技能。这些结果有力地支持了GABA能抑制在运动可塑性中的机制作用，提出了关于运动学习中的群体变异性与大脑中GABA代谢之间的联系的问题。学习新运动技能的能力得到了人脑初级运动皮质结构和功能组织的可塑性的支持。GABA对信号的抑制变化被认为是诱导运动皮质可塑性的关键。本研究利用磁共振波谱(MRS)对运动学习期间、运动期间和静止期间人类运动皮质中的GABA浓度进行了量化。我们报告了MRS测量的特定于学习的GABA浓度降低的证据。此外，学习任务早期的GABA浓度与随后学习的程度密切相关：较高的GABA浓度与较差的学习有关。这些结果初步揭示了与运动学习相关的皮质可塑性的神经化学相关性，特别是在中风康复期间诱导皮质可塑性的治疗努力中。
The ability to learn new motor skills is supported by plasticity in the structural and functional organisation of the primary motor cortex in the human brain. Changes inhibitory to signalling by GABA are thought to be crucial in inducing motor cortex plasticity. This study used magnetic resonance spectroscopy (MRS) to quantify the concentration of GABA in human motor cortex during a period of motor learning, as well as during a period of movement and a period at rest. We report evidence for a reduction in the MRS‐measured concentration of GABA specific to learning. Further, the GABA concentration early in the learning task was strongly correlated with the magnitude of subsequent learning: higher GABA concentrations were associated with poorer learning. The results provide initial insight into the neurochemical correlates of cortical plasticity associated with motor learning, specifically relevant in therapeutic efforts to induce cortical plasticity during recovery from stroke. The ability to learn novel motor skills is a central part of our daily lives and can provide a model for rehabilitation after a stroke. However, there are still fundamental gaps in our understanding of the physiological mechanisms that underpin human motor plasticity. The acquisition of new motor skills is dependent on changes in local circuitry within the primary motor cortex (M1). This reorganisation has been hypothesised to be facilitated by a decrease in local inhibition via modulation of the neurotransmitter GABA, but this link has not been conclusively demonstrated in humans. Here, we used 7 T magnetic resonance spectroscopy to investigate the dynamics of GABA concentrations in human M1 during the learning of an explicit, serial reaction time task. We observed a significant reduction in GABA concentration during motor learning that was not seen in an equivalent motor task lacking a learnable sequence, nor during a passive resting task of the same duration. No change in glutamate was observed in any group. Furthermore, M1 GABA measured early in task performance was strongly correlated with the degree of subsequent learning, such that greater inhibition was associated with poorer subsequent learning. This result suggests that higher levels of cortical inhibition may present a barrier that must be surmounted in order to achieve an increase in M1 excitability, and hence encoding of a new motor skill. These results provide strong support for the mechanistic role of GABAergic inhibition in motor plasticity, raising questions regarding the link between population variability in motor learning and GABA metabolism in the brain. The ability to learn new motor skills is supported by plasticity in the structural and functional organisation of the primary motor cortex in the human brain. Changes inhibitory to signalling by GABA are thought to be crucial in inducing motor cortex plasticity. This study used magnetic resonance spectroscopy (MRS) to quantify the concentration of GABA in human motor cortex during a period of motor learning, as well as during a period of movement and a period at rest. We report evidence for a reduction in the MRS‐measured concentration of GABA specific to learning. Further, the GABA concentration early in the learning task was strongly correlated with the magnitude of subsequent learning: higher GABA concentrations were associated with poorer learning. The results provide initial insight into the neurochemical correlates of cortical plasticity associated with motor learning, specifically relevant in therapeutic efforts to induce cortical plasticity during recovery from stroke.