Soekadar Surjo R, Witkowski Matthias, Cossio Eliana G, Birbaumer Niels, Cohen Leonardo G
Human Cortical Physiology and Neurorehabilitation Section, NINDS, NIH Bethesda, MD, USA ; Applied Neurotechnology Lab, Department of Psychiatry and Psychotherapy, University Hospital Tübingen Tübingen, Germany ; Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen Tübingen, Germany.
Applied Neurotechnology Lab, Department of Psychiatry and Psychotherapy, University Hospital Tübingen Tübingen, Germany ; Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen Tübingen, Germany.
Front Behav Neurosci. 2014 Mar 18;8:93. doi: 10.3389/fnbeh.2014.00093. eCollection 2014.
Transcranial direct current stimulation (tDCS) improves motor learning and can affect emotional processing and attention. However, it is unclear whether learned electroencephalography (EEG)-based brain-machine interface (BMI) control during tDCS is feasible, how application of transcranial electric currents during BMI control would interfere with feature-extraction of physiological brain signals and how it affects brain control performance. Here we tested this combination and evaluated stimulation-dependent artifacts across different EEG frequencies and stability of motor imagery-based BMI control.
Ten healthy volunteers were invited to two BMI-sessions, each comprising two 60-trial blocks. During the trials, learned desynchronization of mu-rhythms (8-15 Hz) associated with motor imagery (MI) recorded over C4 was translated into online cursor movements on a computer screen. During block 2, either sham (session A) or anodal tDCS (session B) was applied at 1 mA with the stimulation electrode placed 1 cm anterior of C4.
tDCS was associated with a significant signal power increase in the lower frequencies most evident in the signal spectrum of the EEG channel closest to the stimulation electrode. Stimulation-dependent signal power increase exhibited a decay of 12 dB per decade, leaving frequencies above 9 Hz unaffected. Analysis of BMI control performance did not indicate a difference between blocks and tDCS conditions.
Application of tDCS during learned EEG-based self-regulation of brain oscillations above 9 Hz is feasible and safe, and might improve applicability of BMI systems.
经颅直流电刺激（tDCS）可改善运动学习，并能影响情绪处理和注意力。然而，尚不清楚在tDCS期间基于脑电图（EEG）的脑机接口（BMI）控制学习是否可行，BMI控制期间经颅电流的施加会如何干扰生理性脑信号的特征提取，以及它如何影响脑控制性能。在此，我们测试了这种组合，并评估了不同EEG频率下与刺激相关的伪迹以及基于运动想象的BMI控制的稳定性。
邀请10名健康志愿者参加两次BMI实验，每次实验包括两个60次试验的组块。在试验过程中，与在C4记录的运动想象（MI）相关的μ节律（8-15Hz）的习得去同步被转化为计算机屏幕上的在线光标移动。在组块2期间，在C4前方1cm处放置刺激电极，以1mA的电流施加假刺激（实验A）或阳极性tDCS（实验B）。
tDCS与低频信号功率显著增加相关，在最靠近刺激电极的EEG通道信号频谱中最为明显。与刺激相关的信号功率增加呈现每十倍频程12dB的衰减，使9Hz以上的频率不受影响。BMI控制性能分析未表明组块和tDCS条件之间存在差异。
在基于EEG的9Hz以上脑振荡的习得性自我调节过程中应用tDCS是可行且安全的，并且可能会提高BMI系统的适用性。
