EURASIP Journal on Applied Signal Processing 
Volume 2005 (2005), Issue 19, Pages 3128-3140
doi:10.1155/ASP.2005.3128

Feature Selection and Blind Source Separation in an EEG-Based Brain-Computer Interface

David A. Peterson,1 James N. Knight,2 Michael J. Kirby,3 Charles W. Anderson,4 and Michael H. Thaut5

 1Department of Computer Science, Center for Biomedical Research in Music, Molecular, Cellular, and Integrative Neurosciences Program and Department of Psychology, Colorado State University, Fort Collins 80523, CO, USA
2Department of Computer Science, Colorado State University, Fort Collins 80523, CO, USA
3Department of Mathematics, Colorado State University, Fort Collins 80523, CO, USA
4Department of Computer Science and Molecular, Cellular, and Integrative Neurosciences Program, Colorado State University, Fort Collins 80523, CO, USA
5Center for Biomedical Research in Music and Molecular, Cellular, and Integrative Neurosciences Program, Colorado State University, Fort Collins 80523, CO, USA
Received 1 February 2004; Revised 14 March 2005

Abstract

Most EEG-based BCI systems make use of well-studied patterns of brain activity. However, those systems involve tasks that indirectly map to simple binary commands such as “yes” or “no” or require many weeks of biofeedback training. We hypothesized that signal processing and machine learning methods can be used to discriminate EEG in a direct “yes”/“no” BCI from a single session. Blind source separation (BSS) and spectral transformations of the EEG produced a 180-dimensional feature space. We used a modified genetic algorithm (GA) wrapped around a support vector machine (SVM) classifier to search the space of feature subsets. The GA-based search found feature subsets that outperform full feature sets and random feature subsets. Also, BSS transformations of the EEG outperformed the original time series, particularly in conjunction with a subset search of both spaces. The results suggest that BSS and feature selection can be used to improve the performance of even a “direct,” single-session BCI.