Department of Biomedical Engineering, School of Medicine, Keimyung University, Daegu, Republic of Korea.
Department of Rehabilitation Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
Cyberpsychol Behav Soc Netw. 2020 Aug;23(8):541-549. doi: 10.1089/cyber.2019.0741. Epub 2020 Jun 1.
Virtual reality (VR) is effectively used to evoke the mirror illusion, and transcranial direct current stimulation (tDCS) synergistically facilitates this illusion. This study investigated whether a mirror virtual hand illusion (MVHI) induced by an immersive, first-person-perspective, virtual mirror system could be modulated by tDCS of the primary motor cortex. Fourteen healthy adults (average age 21.86 years ±0.47, seven men and seven women) participated in this study, and they experienced VR with and without tDCS-the tDCS and sham conditions, each of which takes ∼30 minutes-on separate days to allow the washout of the tDCS effect. While experiencing VR, the movements of the virtual left hand reflected the flexion and extension of the real right hand. Subsequently, electroencephalogram was recorded, the magnitude of the proprioceptive shift was measured, and the participants provided responses to a questionnaire regarding hand ownership. A significant difference in the proprioceptive shift was observed between the tDCS and sham conditions. In addition, there was significant suppression of the mu power in Pz, and augmentation of the beta power in the Pz, P4, O1, and O2 channels. The difference in proprioceptive deviation between the two conditions showed significant negative correlation with mu suppression over the left frontal lobe in the tDCS condition. Finally, the question "I felt that the virtual hand was my own hand" received a significantly higher score under the tDCS condition. In short, applying tDCS over the motor cortex facilitates the MVHI by activating the attentional network over the parietal and frontal lobes such that the MVHI induces more proprioceptive drift, which suggests that the combination of VR and tDCS can enhance the immersive effect in VR. This result provides better support for the use of the MVHI paradigm in combination with tDCS for recovery from illnesses such as stroke.
虚拟现实（VR）可有效地用于唤起镜像错觉，经颅直流电刺激（tDCS）可协同促进这种错觉。本研究调查了沉浸式、第一人称视角的虚拟镜子系统诱导的镜像虚拟手错觉（MVHI）是否可以通过对初级运动皮层的 tDCS 进行调节。14 名健康成年人（平均年龄 21.86 岁±0.47，男性 7 名，女性 7 名）参加了这项研究，他们在不同的日子里分别体验了带有和不带有 tDCS 的 VR（tDCS 和假刺激条件，每种条件约 30 分钟），以允许 tDCS 效果的消退。在体验 VR 的过程中，虚拟左手的运动反映了真实右手的弯曲和伸展。随后记录脑电图，测量本体感受转移的幅度，并让参与者对关于手部所有权的问卷做出回应。在 tDCS 和假刺激条件下观察到本体感受转移的显著差异。此外，在 Pz 上观察到 mu 功率的显著抑制，以及 Pz、P4、O1 和 O2 通道上的 beta 功率的增强。在 tDCS 条件下，两种条件之间的本体感受偏差差异与 mu 抑制在左侧额叶上的差异呈显著负相关。最后，在 tDCS 条件下，“我感觉虚拟手是我自己的手”这个问题得到了更高的分数。总之，在运动皮层上施加 tDCS 通过激活顶叶和额叶的注意网络来促进 MVHI，从而使 MVHI 引起更多的本体感受漂移，这表明 VR 和 tDCS 的结合可以增强 VR 的沉浸式效果。该结果为使用 MVHI 范式与 tDCS 相结合来治疗中风等疾病提供了更好的支持。
