Camus Mickael, Ragert Patrick, Vandermeeren Yves, Cohen Leonardo G
Human Cortical Physiology and Stroke Neurorehabilitation Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20817, USA.
Clin Neurophysiol. 2009 Oct;120(10):1859-65. doi: 10.1016/j.clinph.2009.08.013. Epub 2009 Sep 18.
Training to perform a serial reaction-time task (procedural motor learning) with one hand results in performance improvements in the untrained as well as in the trained hand, a phenomenon referred to as intermanual transfer. The aim of this study was to investigate the neurophysiological changes associated with intermanual transfer associated with learning to perform an eminently different task involving fine force control within the primary motor cortex (M1). We hypothesized that intermanual transfer of learning such a task would reveal intracortical changes within M1.
Speed (time to complete each sequence) and accuracy (% of accuracy errors) of motor performance were measured in both hands before and after right (dominant) hand practice. Transcranial magnetic stimulation (TMS) was used to characterize recruitment curves (RC), short intracortical inhibition (SICI), intracortical facilitation (ICF) and interhemispheric inhibition (IHI) from the left to the right M1.
Practice resulted in significant improvements in both speed and accuracy in the right trained hand and in the left untrained hand. RC increased in the left M1, SICI decreased in both M1s, and IHI from the left to the right M1 decreased. No changes were identified in ICF nor in RC in the right M1.
Our results suggest that some neurophysiological mechanisms operating in the M1 controlling performance of an untrained hand may contribute to optimize the procedure for selecting and implementing correct pinch force levels.
These results raise the hypothesis of a contribution of modulation of SICI and IHI, or an interaction between both to intermanual transfer after learning a sequential pinch force task.
用一只手进行序列反应时任务（程序性运动学习）的训练会使未训练的手以及训练过的手的表现得到改善，这种现象被称为双侧间迁移。本研究的目的是调查与在初级运动皮层（M1）内学习执行一项涉及精细力量控制的截然不同的任务相关的双侧间迁移所伴随的神经生理学变化。我们假设学习这样一项任务的双侧间迁移会揭示M1内的皮质内变化。
在右手（优势手）练习前后，测量双手的运动表现速度（完成每个序列的时间）和准确性（准确性错误的百分比）。经颅磁刺激（TMS）用于表征从左侧M1到右侧M1的募集曲线（RC）、短皮质内抑制（SICI）、皮质内易化（ICF）和半球间抑制（IHI）。
练习使右侧训练手和左侧未训练手的速度和准确性都有显著提高。左侧M1的RC增加，双侧M1的SICI降低，从左侧M1到右侧M1的IHI降低。右侧M1的ICF和RC均未发现变化。
我们的结果表明，在M1中控制未训练手表现的一些神经生理机制可能有助于优化选择和实施正确捏力水平的程序。
这些结果提出了一个假设，即SICI和IHI的调节或两者之间的相互作用对学习顺序捏力任务后的双侧间迁移有贡献。
