Neuromed Institute (IRCCS), Pozzilli, Isernia, Italy.
Department of Neurology and Psychiatry, Sapienza University of Rome, Italy.
Brain Stimul. 2015 May-Jun;8(3):603-12. doi: 10.1016/j.brs.2015.01.405. Epub 2015 Jan 21.
Motor training usually increases the excitability of corticospinal outputs to the trained muscles. However, it is uncertain to what extent the change in excitability is a critical component of behavioral learning or whether it is a non-specific side effect.
OBJECTIVE/HYPOTHESIS: We used a depotentiation protocol to abolish the training-induced increase of corticospinal excitability and tested whether this had any immediate effect on the improved motor performance.
We used an index finger abduction task in which behavioral improvement is known to be associated with M1 excitability changes as monitored by the amplitude of motor-evoked potentials produced by single-pulse transcranial magnetic stimulation (TMS). These effects could be reversed by a depotentiation protocol using a short form of continuous theta-burst stimulation (cTBS150). Participants underwent three experimental interventions: 'motor training', 'motor training plus cTBS150' and 'cTBS150'. M1 excitability and TMS-evoked finger movements were assessed before the experimental interventions and 5 min, 15 min, and 30 min thereafter. Motor retention was tested 45 min after the experimental interventions.
During training, acceleration of the practiced movement improved. At the end of training, M1 excitability and the acceleration of TMS-evoked index finger movements in the direction of training had increased and the enhanced performance was retained when tested 45 min later. The depotentiation protocol, delivered immediately after the end of training, reversed the excitability changes in M1 but did not affect the acceleration of the TMS-evoked finger movement nor the retention of performance. The depotentiation protocol alone did not modify M1 excitability.
The present study indicates that in the short term, increases in corticospinal excitability are not related to immediate changes in behavioral motor outcome.
运动训练通常会增加皮质脊髓输出到训练肌肉的兴奋性。然而，兴奋性的变化在多大程度上是行为学习的关键组成部分，或者它是否是一种非特异性的副作用，还不确定。
目的/假设：我们使用去敏化方案来消除训练引起的皮质脊髓兴奋性增加，并测试这种变化是否会对运动表现的改善产生直接影响。
我们使用了一个食指外展任务，在这个任务中，已知行为改善与 M1 兴奋性变化有关，可以通过监测由单次经颅磁刺激（TMS）产生的运动诱发电位的幅度来监测。这些效应可以通过使用短形式的连续 theta 爆发刺激（cTBS150）的去敏化方案来逆转。参与者接受了三种实验干预：“运动训练”、“运动训练加 cTBS150”和“cTBS150”。在实验干预之前、之后的 5 分钟、15 分钟和 30 分钟评估 M1 兴奋性和 TMS 诱发的手指运动。在实验干预后 45 分钟测试运动保持情况。
在训练过程中，练习运动的加速得到了提高。在训练结束时，M1 兴奋性和 TMS 诱发的食指在训练方向上的运动加速增加，在 45 分钟后测试时，增强的性能得到保持。在训练结束后立即进行的去敏化方案逆转了 M1 中的兴奋性变化，但对 TMS 诱发的手指运动的加速或性能的保持没有影响。单独的去敏化方案本身不会改变 M1 兴奋性。
本研究表明，在短期内，皮质脊髓兴奋性的增加与行为运动结果的即时变化无关。
