The Brain and Mind Institute, Western University, London, Ontario, Canada.
Department of Computer Science, Western University, London, Ontario, Canada.
J Neurophysiol. 2020 May 1;123(5):1727-1738. doi: 10.1152/jn.00054.2020. Epub 2020 Mar 25.
Beyond being essential for long-term motor-skill development, movement repetition has immediate benefits on performance, increasing speed and accuracy of a second execution. While repetition effects have been reported for single reaching movements, it has yet to be determined whether they also occur for movement sequences, and what aspects of sequence production are improved. We addressed these questions in two behavioral experiments using a discrete sequence production (DSP) task in which human volunteers had to perform short sequences of finger movements. In , we presented participants with randomly varying sequences and manipulated ) whether the same sequence was repeated on successive trials and ) whether participants had to execute the sequence (Go) or not (No-Go). We establish that sequence repetition led to immediate improvements in speed without associated accuracy costs. The largest benefit was observed in the middle part of a sequence, suggesting that sequence repetition facilitated online planning. This claim was further supported by , in which we kept a set of sequences fixed throughout the experiment, thus allowing participants to develop sequence-specific learning: once the need for online planning decreased, the benefit of repetition disappeared. Finally, we found that repetition-related improvements only occurred for the trials that had been preceded by sequence production, suggesting that action selection and sequence preplanning may not be sufficient to reap the benefits of repetition. Together, these results show that repetition can enhance representations at the level of movement sequences (rather than of individual movements) and facilitate online planning. Even for overlearned motor skills such as reaching, movement repetition improves performance. How brain processes associated with motor planning or execution benefit from repetition, however, remains unclear. We report the novel finding of repetition effects for sequential movements. Our results show that repetition benefits are tied to improved online planning of upcoming sequence elements. We also highlight how actual movement experience appears to be more beneficial than mental rehearsal for observing short-term repetition effects.
除了对长期运动技能发展至关重要外，运动重复还能立即提高表现，加快和提高第二次执行的速度和准确性。虽然已经报道了单个到达运动的重复效应，但尚不清楚它们是否也适用于运动序列，以及序列产生的哪些方面得到了改善。我们在两项行为实验中使用离散序列产生 (DSP) 任务来解决这些问题，在该任务中，人类志愿者必须执行短序列的手指运动。在[1]中，我们向参与者展示了随机变化的序列，并操纵了)在连续试验中是否重复相同的序列，以及)参与者是否必须执行序列（Go）或不执行（No-Go）。我们确定序列重复导致速度立即提高，而不会导致准确性降低。最大的好处是在序列的中间部分观察到，这表明序列重复促进了在线规划。这一说法在[2]中得到了进一步支持，在该实验中，我们在整个实验过程中保持一组序列固定，从而允许参与者发展特定于序列的学习：一旦不再需要在线规划，重复的好处就会消失。最后，我们发现只有在之前进行过序列产生的试验中才会出现与重复相关的改进，这表明动作选择和序列预规划可能不足以获得重复的好处。总之，这些结果表明，重复可以增强运动序列（而不是单个运动）的表示，并促进在线规划。即使是像伸手这样的高度熟练的运动技能，运动重复也可以提高表现。然而，与运动规划或执行相关的大脑过程如何从重复中受益，目前仍不清楚。我们报告了序列运动的重复效应的新发现。我们的结果表明，重复的好处与即将到来的序列元素的在线规划改善有关。我们还强调了实际运动经验如何比心理演练更有利于观察短期重复效应。
