Towards Multi-class Pre-movement Classification

TL;DR

This paper introduces a novel spectral filtering method, SASF, combined with RTRCA framework, significantly improving multi-class pre-movement EEG classification accuracy for non-invasive brain-computer interfaces.

Contribution

It proposes the SASF method within RTRCA for enhanced multi-class pre-movement EEG decoding, outperforming existing approaches.

Findings

Achieves 96.7% accuracy in binary classification, outperforming CNN and DSP methods.

Attains 94.9% accuracy in 7-class classification, demonstrating effectiveness.

Enables decoding of movement from EEG signals before actual limb movement.

Abstract

In non-invasive brain-computer interface systems, pre-movement decoding plays an important role in the detection of movement before limbs actually move. Movement-related cortical potential is a kind of brain activity associated with pre-movement decoding. In current studies, patterns decoded from movement are mainly applied to the binary classification between movement state and resting state, such as elbow flexion and rest. The classifications between two movement states and among multiple movement states are still challenging. This study proposes a new method, the star-arrangement spectral filtering (SASF), to solve the multi-class pre-movement classification problem. We first design a referenced task-related component analysis (RTRCA) framework that consists of two modules. This first module is the classification between movement state and resting state; the second module is the classification of multiple movement states. SASF is developed by optimizing the features in RTRCA. In SASF, feature selection on filter banks is used on the first module of RTRCA, and feature selection on time windows is used on the second module of RTRCA. A linear discriminant analysis classifier is used to classify the optimized features. In the binary classification between two motions, the classification accuracy of SASF achieves 0.9670$\pm$0.0522, which is significantly higher than the result provided by the deep convolutional neural network (0.6247$\pm$0.0680) and the discriminative spatial pattern method (0.4400$\pm$0.0700). In the multi-class classification of 7 states, the classification accuracy of SASF is 0.9491$\pm$0.0372. The proposed SASF greatly improves the classification between two motions and enables the classification among multiple motions. The result shows that the movement can be decoded from EEG signals before the actual limb movement.