Feature Reweighting for EEG-based Motor Imagery Classification

TL;DR

This paper introduces a feature reweighting module for CNNs that suppresses irrelevant EEG features, significantly improving motor imagery classification accuracy on benchmark datasets.

Contribution

It proposes a novel feature reweighting approach that enhances CNN-based MI-EEG classification by reducing noise and irrelevant features, leading to better performance.

Findings

Achieved 9.34% accuracy improvement on Physionet EEG-MMIDB dataset.

Achieved 3.82% accuracy improvement on BCI Competition IV 2a dataset.

Demonstrated significant performance gains over state-of-the-art methods.

Abstract

Classification of motor imagery (MI) using non-invasive electroencephalographic (EEG) signals is a critical objective as it is used to predict the intention of limb movements of a subject. In recent research, convolutional neural network (CNN) based methods have been widely utilized for MI-EEG classification. The challenges of training neural networks for MI-EEG signals classification include low signal-to-noise ratio, non-stationarity, non-linearity, and high complexity of EEG signals. The features computed by CNN-based networks on the highly noisy MI-EEG signals contain irrelevant information. Subsequently, the feature maps of the CNN-based network computed from the noisy and irrelevant features contain irrelevant information. Thus, many non-contributing features often mislead the neural network training and degrade the classification performance. Hence, a novel feature reweighting approach is proposed to address this issue. The proposed method gives a noise reduction mechanism named feature reweighting module that suppresses irrelevant temporal and channel feature maps. The feature reweighting module of the proposed method generates scores that reweight the feature maps to reduce the impact of irrelevant information. Experimental results show that the proposed method significantly improved the classification of MI-EEG signals of Physionet EEG-MMIDB and BCI Competition IV 2a datasets by a margin of 9.34% and 3.82%, respectively, compared to the state-of-the-art methods.