Increasing of coherence intensity at alpha and theta frequency band during both of visuomotor skill learning and interlimb transfer process across hands

概要

（書式１８）

学
（

位 論 文 要 約
A b s t r a c t ）

博士論文題目 Title of dissertation
Increasing of coherence intensity at alpha and theta frequency band during both of visuomotor skill learning and
interlimb transfer process across hands
(視覚運動技能学習と肢間転移の過程における α および θ 周波数帯のコヒーレンス強度の増加)
東北大学大学院医学系研究科

障害科学

専攻

機能医科学 講座 運動学 分野
氏名 Name 趙軍（ZHAO JUN）
Motor learning is an asymptotic process that emerges as an interplay between the cognitive and motor systems, in which
repeated practice gradually enables appropriate movements. Humans have a delicate system and remarkable capacity to
learn new motor skills and generalize the acquired new skills across the hands, known as interlimb transfer. It holds
promise in facilitating behavioral flexibility and adaptation to similar tasks using untrained hands. For example, it can be
used in clinical neurorehabilitation for the functional recovery of a weak hand after a stroke by training the
non-paralyzed hand. Therefore, it is fundamentally important to understand the neurocognitive mechanisms underlying
motor skill learning and the transfer of motor skills across the hands. However, the neurophysiological dynamics
underlying visuomotor skill learning and how these dynamic representations are transferred to the untrained hand are
poorly understood. Under the hypothesis that successful interlimb transfer and visuomotor skill learning could share
common mechanisms, we designed a randomized controlled study in which 48 right-handed participants were randomly
assigned into 4 groups: ‘left-hand simple task training’, ‘left-hand complex task training, ‘right-hand simple task
training’, and ‘right-hand complex task training’ They performed 10 blocks of assigned visuomotor skill learning. The
training effect of trained hand and the transfer effect of the untrained hand were evaluated after the training. Brain
activity was monitored with a high-density electroencephalogram (EEG) throughout the training and skill evaluation.
Forty-seven participants completed the tasks. Behaviorally, we showed that the degree of motor learning and interlimb
transfer varied as a function of task complexity and dominance of the trained hand. Neuronally, in a complex task
involving the training of the right dominant hand, 1) enhanced alpha coherence between the left primary motor cortex
and supplementary motor area; and 2) enhanced theta coherence between the left frontal and centroparietal cortex, were
consistently shown across training and transfer sessions. Moreover, in a complex task involving the training of the left
non-dominant hand, enhanced theta coherence between the left primary motor cortex and centroparietal cortex was
consistently shown across training and transfer sessions. Altogether, our results suggest that the functional connectivity
among the motor cortex, including M1 and SMA, frontal and parietal regions are associated with both visuomotor skill
learning and interlimb transfer performance. The visuomotor skill learning and interlimb transfer were also susceptible to
the task complexity and the dominance of the trained hand. To the best of our knowledge, our study is the first that has
identified the unique representation of neurophysiological commonality across visuomotor skill learning and interlimb
transfer that was also modulated by task complexity and the dominance of the trained hand. Our findings may provide a
neurocognitive account of how newly acquired visuomotor skills were generalized across hands. ...