Department of Bioengineering, George Mason University, Fairfax, Virginia.
Department of Neuroscience, George Mason University, Fairfax, Virginia.
J Neurophysiol. 2019 Sep 1;122(3):933-946. doi: 10.1152/jn.00569.2018. Epub 2019 Jul 10.
Humans rapidly adapt reaching movements in response to perturbations (e.g., manipulations of movement dynamics or visual feedback). Following a break, when reexposed to the same perturbation, subjects demonstrate savings, a faster learning rate compared with the time course of initial training. Although this has been well studied, there are open questions on the extent early savings reflects the rapid recall of previous performance. To address this question, we examined how the properties of initial training (duration and final adaptive state) influence initial single-trial adaptation to force-field perturbations when training sessions were separated by 24 h. There were two main groups that were distinct based on the presence or absence of a washout period at the end of (with washout vs. without washout). We also varied the training duration on (15, 30, 90, or 160 training trials), resulting in 8 subgroups of subjects. We show that single-trial adaptation on scaled with training duration, even for similar asymptotic levels of learning on of training. Interestingly, the temporal force profile following the first perturbation on matched that at the end of for the longest training duration group that did not complete the washout. This correspondence persisted but was significantly lower for shorter training durations and the washout subject groups. Collectively, the results suggest that the adaptation observed very early in reexposure results from the rapid recall of the previously learned motor recalibration but is highly dependent on the initial training duration and final adaptive state. The extent initial readaptation reflects the recall of previous motor performance is largely unknown. We examined early single-trial force-field adaptation on the second day of training and distinguished initial retention from recall. We found that the single-trial adaptation following the 24-h break matched that at the end of the first day, but this recall was modified by the training duration and final level of learning on the first day of training.
人类可以迅速适应运动中的各种干扰（例如，运动动力学或视觉反馈的变化）。在中断后重新暴露于相同的干扰时，与初始训练的时间进程相比，被试会表现出节省，即更快的学习速度。尽管这已经得到了很好的研究，但仍有一些问题尚未解决，例如早期节省在多大程度上反映了对先前表现的快速回忆。为了解决这个问题，我们研究了当训练间隔为 24 小时时，初始训练的性质（持续时间和最终适应状态）如何影响初始单次试验对力场干扰的适应。主要有两组，一组是在结束时是否有冲洗期（有冲洗期和无冲洗期）。我们还改变了在（15、30、90 或 160 个训练试验）上的训练持续时间，结果产生了 8 个不同的被试小组。我们表明，即使在相似的训练结束时的学习水平下，在（有冲洗期和无冲洗期）上的单次试验适应也与训练持续时间成正比。有趣的是，在最长的无冲洗训练持续时间组中，第一次干扰后的时间力场与在没有完成冲洗的情况下的训练结束时的力场相匹配。这种对应关系持续存在，但对于较短的训练持续时间和冲洗组的被试来说，要低得多。总的来说，这些结果表明，在重新暴露时观察到的适应性是由先前学习的运动重新校准的快速回忆引起的，但高度依赖于初始训练持续时间和最终适应状态。初始重新适应在多大程度上反映了先前运动表现的回忆，目前尚不清楚。我们研究了在第二天训练时的早期单次试验力场适应，并区分了初始保留和回忆。我们发现，在 24 小时休息后，单次试验的适应与第一天结束时的适应相匹配，但这种回忆受到第一天训练的持续时间和最终学习水平的影响。
