EEG data MiEEG data Mirror Visual Feedback with electrical painful and non-painful stimulationsrror Visual Feedback with electrical painful and non-painful stimulations

Experimental procedure:The participants were comfortably seated on a chair with their arms lying symmetrically ahead on a table. Auditory cues of 70 dB, 1000 Hz, and 50 ms of duration (Kida et al., 2006) were used to trigger right index finger movements. All the subjects underwent three different conditions (80 trials each) in randomized order. Each condition lasted approx. 13 min with 10 min breaks between the conditions. The whole session – including EEG net preparation, training, pain threshold measurement, and experiment – lasted approx. 2.5 hours. In the experimental condition (Unilateral with Mirror, or UM+), the mirror was placed on the desk, perpendicularly to the subjects’ midsagittal plane with the reflecting face on the right side (Figure 1). Subjects were instructed to move the right index finger in response to the auditory cue while watching the image of the reflected moving hand in the mirror to give the illusion of the simultaneous left index finger movement. The position of the left hand behind the mirror corresponded to the image of the left hand reflected in the mirror. In the control conditions, the mirror was removed from the experimental setting and the left hand was directly visible to the participants. In one control condition (Unilateral without Mirror, UM-), subjects were asked to perform the same unilateral right index finger movements. In the other control condition (Bilateral without Mirror, BM-), subjects had to perform synchronous movements of both index fingers. The movements consisted of a double extension of the index finger with a slow release toward the bottom (approx. 1 s). All the participants received a brief training to perform the movement correctly and keep the left hand as still as possible during the unilateral conditions. In each condition, an electrical stimulus was delivered on the tip of the left index finger 100 ms after the auditory cue to induce cortical sensory-motor interaction (Figure 2). The interval between the stimuli was fixed at 10 s, a sufficient period to reset the desynchronization of the alpha rhythms (Babiloni et al., 2008). A fixed interval also allowed to produce a sort of predictability of the upcoming auditory and electrical stimuli, optimal to study the anticipatory alpha ERD/ERS responses. However, subjects were not informed of this fixed interval to avoid any counting strategies. EEG data are uploaded in .hdf5 extension (g.recorder amplifier) to be analyzed with EEGLAB toolbox for MATLAB.Raw data coding slightly differs from the one presented in the original manuscript:no-M+P = UM-no-M+P-bil = BM-yes-M+P = UM+

实验流程：受试者舒适就坐于座椅，双臂对称前伸置于桌面。采用70 dB、1000 Hz、时长50 ms的听觉提示音（Kida等，2006）触发右侧食指运动。所有受试者以随机顺序完成3种不同实验条件，每种条件包含80次试次，单条件持续约13分钟，条件间设置10分钟休息。整个实验流程——包括脑电帽（EEG net）佩戴准备、动作训练、痛阈测量及正式实验——总时长约2.5小时。
实验条件（单侧镜像条件，UM+）：将镜子放置于桌面，垂直于受试者正中矢状面，镜面朝向右侧（图1）。要求受试者根据听觉提示音移动右侧食指，同时观察镜中反射的运动手部影像，以产生左侧食指同步运动的错觉。镜后方的左手位置与镜中反射的左手影像完全对应。
对照条件：移除实验设置中的镜子，受试者可直接观察左手。其中一种对照条件（单侧无镜像条件，UM-）：要求受试者完成与实验条件一致的右侧食指单侧运动。另一种对照条件（双侧无镜像条件，BM-）：要求受试者完成双侧食指同步运动。
本次运动为食指两次伸展后缓慢下放至初始位置，单动作时长约1秒。所有受试者均接受简短训练，以确保正确完成动作，并在单侧运动条件下尽可能保持左手静止。
每种条件下，在听觉提示音出现100 ms后，对左侧食指指尖施加电刺激，以诱发皮层感觉-运动交互反应（图2）。刺激间隔固定为10秒，该时长足以重置α节律的去同步化状态（Babiloni等，2008）。固定间隔还可使即将到来的听觉与电刺激具备可预测性，这一特性最适于研究预期性α事件相关去同步化/事件相关同步化（Event-Related Desynchronization/Event-Related Synchronization, ERD/ERS）响应。但受试者并未被告知该固定间隔，以避免其采用计数策略。
实验数据以.hdf5格式（配套g.recorder放大器采集）上传，可使用MATLAB的EEGLAB工具箱进行分析。原始数据编码与原手稿略有差异：no-M+P = UM-；no-M+P-bil = BM-；yes-M+P = UM+