Optimizing Brain-Computer Interface Performance: Advancing EEG Signals Channel Selection through Regularized CSP and SPEA II Multi-Objective Optimization
M. Moein Esfahani, Hossein Sadati, Vince D Calhoun
TL;DR
This work tackles efficient channel selection for MI-BCI systems by pairing Regularized CSP (RCSP) feature extraction with the Strength Pareto Evolutionary Algorithm II (SPEA-II) to optimize subject-specific channel subsets. The methodology integrates High Laplacian source localization, targeted bandpass filtering, and ensemble classification to mitigate noise and overfitting while maintaining high accuracy with fewer electrodes. Key contributions include a RCSP-based penalty formulation $J_{P_{1,2}}(w) = \frac{w^T \tilde{C}_{1,2} w}{w^T \tilde{C}_{2,1} w + \alpha P(w)}$ and a wrapper-channel-selection framework guided by Pareto fronts, evaluated on BCI Competition IV-Dataset1 with 10-fold cross-validation. The results demonstrate improved MI-BCI performance with reduced channel counts, offering practical benefits for user comfort and setup efficiency and suggesting avenues for future MOEA exploration (e.g., MOEAD, MOPSO).
Abstract
Brain-computer interface systems and the recording of brain activity has garnered significant attention across a diverse spectrum of applications. EEG signals have emerged as a modality for recording neural electrical activity. Among the methodologies designed for feature extraction from EEG data, the method of RCSP has proven to be an approach, particularly in the context of MI tasks. RCSP exhibits efficacy in the discrimination and classification of EEG signals. In optimizing the performance of this method, our research extends to a comparative analysis with conventional CSP techniques, as well as optimized methodologies designed for similar applications. Notably, we employ the meta-heuristic multi-objective Strength Pareto Evolutionary Algorithm II (SPEA-II) as a pivotal component of our research paradigm. This is a state-of-the-art approach in the selection of an subset of channels from a multichannel EEG signal with MI tasks. Our main objective is to formulate an optimum channel selection strategy aimed at identifying the most pertinent subset of channels from the multi-dimensional electroencephalogram (EEG) signals. One of the primary objectives inherent to channel selection in the EEG signal analysis pertains to the reduction of the channel count, an approach that enhances user comfort when utilizing gel-based EEG electrodes. Additionally, within this research, we took benefit of ensemble learning models as a component of our decision-making. This technique serves to mitigate the challenges associated with overfitting, especially when confronted with an extensive array of potentially redundant EEG channels and data noise. Our findings not only affirm the performance of RCSP in MI-based BCI systems, but also underscore the significance of channel selection strategies and ensemble learning techniques in optimizing the performance of EEG signal classification.