Data from: Investigating the impact of feedback update interval on the efficacy of restorative brain–computer interfaces

Restorative brain–computer interfaces (BCIs) have been proposed to enhance stroke rehabilitation. Restorative BCIs are able to close the sensorimotor loop by rewarding motor imagery (MI) with sensory feedback. Despite the promising results from early studies, reaching clinically significant outcomes in a timely fashion is yet to be achieved. This lack of efficacy may be due to suboptimal feedback provision. To the best of our knowledge, the optimal feedback update interval (FUI) during MI remains unexplored. There is evidence that sensory feedback disinhibits the motor cortex. Thus, in this study, we explore how shorter than usual FUIs affect behavioural and neurophysiological measures following BCI training for stroke patients using a single-case proof-of-principle study design. The action research arm test was used as the primary behavioural measure and showed a clinically significant increase (36%) over the course of training. The neurophysiological measures including motor evoked potentials and maximum voluntary contraction showed distinctive changes in early and late phases of BCI training. Thus, this preliminary study may pave the way for running larger studies to further investigate the effect of FUI magnitude on the efficacy of restorative BCIs. It may also elucidate the role of early and late phases of motor learning along the course of BCI training.

修复性脑机接口（Restorative brain–computer interfaces, BCIs）已被提出用于改善脑卒中康复。此类修复性BCIs可通过为运动想象（motor imagery, MI）提供感觉反馈来闭合感觉运动环路（sensorimotor loop）。尽管早期研究已取得颇具前景的成果，但目前仍未能实现及时获得临床显著疗效的目标。这种疗效不足的情况可能源于反馈提供方式欠佳。据我们所知，运动想象过程中的最优反馈更新间隔（optimal feedback update interval, FUI）仍未得到相关探索。已有研究表明，感觉反馈可解除运动皮层（motor cortex）的抑制状态。因此，本研究采用单案例原理验证研究设计（single-case proof-of-principle study design），探索相较于常规更短的FUI对脑卒中患者接受BCI训练后的行为学与神经生理学指标（behavioural and neurophysiological measures）的影响。本研究以动作研究上肢测试（action research arm test）作为主要行为学指标，结果显示训练过程中该指标出现了具有临床意义的36%提升。包括运动诱发电位（motor evoked potentials）与最大自主收缩量（maximum voluntary contraction）在内的神经生理学指标，在BCI训练的早期与晚期阶段呈现出特征性变化。因此，这项初步研究可为开展更大规模的研究以进一步探究FUI量级对修复性BCIs疗效的影响铺平道路，同时也有望阐明运动学习的早晚期阶段在BCI训练过程中的作用。