Wolpaw J R, Flotzinger D, Pfurtscheller G, McFarland D J
Wadsworth Center for Laboratories and Research, New York State Department of Health and State University of New York, Albany 12201-0509, USA.
J Clin Neurophysiol. 1997 Nov;14(6):529-38. doi: 10.1097/00004691-199711000-00010.
Recent studies show that humans can learn to control the amplitude of electroencephalography (EEG) activity in specific frequency bands over sensorimotor cortex and use it to move a cursor to a target on a computer screen. EEG-based communication could be a valuable new communication and control option for those with severe motor disabilities. Realization of this potential requires detailed knowledge of the characteristic features of EEG control. This study examined the course of EEG control after presentation of a target. At the beginning of each trial, a target appeared at the top or bottom edge of the subject's video screen and 1 sec later a cursor began to move vertically as a function of EEG amplitude in a specific frequency band. In well-trained subjects, this amplitude was high at the time the target appeared and then either remained high (i.e., for a top target) or fell rapidly (i.e., for a bottom target). Target-specific EEG amplitude control began 0.5 sec after the target appeared and appeared to wax and wane with a period of approximately 1 sec until the cursor reached the target (i.e., a hit) or the opposite edge of the screen (i.e., a miss). Accuracy was 90% or greater for each subject. Top-target errors usually occurred later in the trial because of failure to reach and/or maintain sufficiently high amplitude, whereas bottom-target errors usually occurred immediately because of failure to reduce an initially high amplitude quickly enough. The results suggest modifications that could improve performance. These include lengthening the intertrial period, shortening the delay between target appearance and cursor movement, and including time within the trial as a variable in the equation that translates EEG into cursor movement.
近期研究表明，人类能够学会控制感觉运动皮层特定频段脑电图（EEG）活动的幅度，并利用其将电脑屏幕上的光标移动至目标位置。基于脑电图的通信对于严重运动功能障碍者而言，可能是一种有价值的新型通信与控制方式。要实现这一潜力，需要详细了解脑电图控制的特征。本研究考察了呈现目标后脑电图控制的过程。在每次试验开始时，一个目标出现在受试者视频屏幕的顶部或底部边缘，1秒后，一个光标开始根据特定频段脑电图的幅度垂直移动。在训练有素的受试者中，目标出现时该幅度较高，然后要么保持较高水平（即对于顶部目标），要么迅速下降（即对于底部目标）。目标特异性脑电图幅度控制在目标出现后0.5秒开始，并且在光标到达目标（即命中）或屏幕的对边（即未命中）之前，似乎以大约1秒的周期起伏变化。每个受试者的准确率达到90%或更高。顶部目标错误通常在试验后期出现，原因是未能达到和/或保持足够高的幅度，而底部目标错误通常立即出现，原因是未能足够快地降低初始的高幅度。结果表明了一些可以提高性能的改进措施。这些措施包括延长试验间隔时间、缩短目标出现与光标移动之间的延迟，以及将试验中的时间作为将脑电图转换为光标移动的方程中的一个变量。
