Suresh Tharan, Iwane Fumiaki, Zhang Minsu, McElmurry Margaret, Manesiya Muskan, Freedberg Michael V, Hussain Sara J
Department of Kinesiology & Health Education, The University of Texas at Austin, Austin, Texas, United States.
Human Cortical Physiology and Neurorehabilitation Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States.
J Neurophysiol. 2025 Jul 1;134(1):250-263. doi: 10.1152/jn.00579.2024. Epub 2025 Jun 11.
Motor cortical (M1) transcranial magnetic stimulation (TMS) interventions increase corticospinal output and improve motor learning when delivered during sensorimotor mu rhythm trough but not peak phases, suggesting that the mechanisms supporting motor learning may be most active during mu trough phases. Based on these findings, we predicted that motor sequence learning-related corticospinal plasticity would be most evident when measured during mu trough phases. Healthy adults were assigned to either a sequence or no-sequence group. Participants in the sequence group practiced the implicit serial reaction time task (SRTT), which contained an embedded, repeating 12-item sequence. Participants in the no-sequence group practiced a version of the SRTT that contained no sequence. We measured mu phase-independent and mu phase-dependent MEP amplitudes using EEG-informed single-pulse TMS before, immediately after, and 30 min after the SRTT in both groups. All participants performed a retention test 1 h after SRTT acquisition. In both groups, mu phase-independent MEP amplitudes increased following SRTT acquisition, but the pattern of mu phase-dependent MEP amplitude changes after SRTT acquisition differed between groups. Relative to the no-sequence group, the sequence group showed greater peak-specific MEP amplitude increases 30 min after SRTT acquisition. Furthermore, the magnitude of these peak-specific MEP amplitude increases was negatively associated with the magnitude of sequence learning. Contrary to our original hypothesis, results revealed that motor sequence learning elicits peak-specific corticospinal plasticity. Findings provide first direct evidence that motor sequence learning recruits mu phase-dependent neurophysiological processes in the human brain. Recent work suggests that motor learning's neural mechanisms may be most active during specific sensorimotor mu rhythm phases. If so, motor sequence learning-induced corticospinal plasticity should be more evident during some mu phases than others. Our results show that motor sequence learning elicits corticospinal plasticity that is most prominent during mu peak phases. Furthermore, this peak-specific plasticity correlates with learning. Findings provide first evidence that motor learning elicits mu phase-dependent plasticity in the human brain.
运动皮层（M1）经颅磁刺激（TMS）干预在感觉运动μ节律波谷而非峰值阶段进行时，会增加皮质脊髓输出并改善运动学习，这表明支持运动学习的机制可能在μ波谷阶段最为活跃。基于这些发现，我们预测，当在μ波谷阶段进行测量时，与运动序列学习相关的皮质脊髓可塑性将最为明显。健康成年人被分为序列组或无序列组。序列组的参与者练习内隐序列反应时任务（SRTT），该任务包含一个嵌入的、重复的12项序列。无序列组的参与者练习不含序列的SRTT版本。我们在两组SRTT之前、之后立即以及之后30分钟，使用脑电图辅助单脉冲TMS测量了与μ相位无关和与μ相位相关的运动诱发电位（MEP）幅度。所有参与者在SRTT获取后1小时进行了一次保持测试。在两组中，SRTT获取后与μ相位无关的MEP幅度均增加，但SRTT获取后与μ相位相关的MEP幅度变化模式在两组之间有所不同。相对于无序列组，序列组在SRTT获取后30分钟显示出更大的特定峰值MEP幅度增加。此外，这些特定峰值MEP幅度增加的幅度与序列学习的幅度呈负相关。与我们最初的假设相反，结果显示运动序列学习会引发特定峰值的皮质脊髓可塑性。研究结果提供了首个直接证据，表明运动序列学习会在人类大脑中引发与μ相位相关的神经生理过程。最近的研究表明，运动学习的神经机制可能在特定的感觉运动μ节律阶段最为活跃。如果是这样，运动序列学习诱导的皮质脊髓可塑性在某些μ相位应该比其他相位更明显。我们的结果表明，运动序列学习会引发皮质脊髓可塑性，这种可塑性在μ峰值阶段最为突出。此外，这种特定峰值的可塑性与学习相关。研究结果提供了首个证据，表明运动学习会在人类大脑中引发与μ相位相关的可塑性。
