Increasing BCI communication rates with dynamic stopping towards more practical use: an ALS study

• Published in: Journal of neural engineering 2015-02, Vol.12 (1), p.016013-016013
• Main Authors: Mainsah, B O, Collins, L M, Colwell, K A, Sellers, E W, Ryan, D B, Caves, K, Throckmorton, C S
• Format: Article
• Language: English
• Subjects: Adult; Algorithms; amyotrophic lateral sclerosis; Amyotrophic Lateral Sclerosis - physiopathology; Amyotrophic Lateral Sclerosis - rehabilitation; Bayesian dynamic stopping; Brain; Brain Mapping - methods; Brain-Computer Interfaces; Communication Aids for Disabled; Computer Peripherals; Data acquisition; Dynamic tests; Dynamics; Electroencephalography - methods; Event-Related Potentials, P300; Female; Human-computer interface; Humans; Information Storage and Retrieval - methods; Male; Middle Aged; Online; P300 speller; Pattern Recognition, Automated - methods; Populations; Reproducibility of Results; Sensitivity and Specificity; Signal Processing, Computer-Assisted; Visual Cortex - physiopathology; Visual Perception; Word Processing
• ISSN: 1741-2560; 1741-2552
• DOI: 10.1088/1741-2560/12/1/016013

Objective. The P300 speller is a brain-computer interface (BCI) that can possibly restore communication abilities to individuals with severe neuromuscular disabilities, such as amyotrophic lateral sclerosis (ALS), by exploiting elicited brain signals in electroencephalography (EEG) data. However, accurate spelling with BCIs is slow due to the need to average data over multiple trials to increase the signal-to-noise ratio (SNR) of the elicited brain signals. Probabilistic approaches to dynamically control data collection have shown improved performance in non-disabled populations; however, validation of these approaches in a target BCI user population has not occurred. Approach. We have developed a data-driven algorithm for the P300 speller based on Bayesian inference that improves spelling time by adaptively selecting the number of trials based on the acute SNR of a user's EEG data. We further enhanced the algorithm by incorporating information about the user's language. In this current study, we test and validate the algorithms online in a target BCI user population, by comparing the performance of the dynamic stopping (DS) (or early stopping) algorithms against the current state-of-the-art method, static data collection, where the amount of data collected is fixed prior to online operation. Main results. Results from online testing of the DS algorithms in participants with ALS demonstrate a significant increase in communication rate as measured in bits min (100-300%), and theoretical bit rate (100-550%), while maintaining selection accuracy. Participants also overwhelmingly preferred the DS algorithms. Significance. We have developed a viable BCI algorithm that has been tested in a target BCI population which has the potential for translation to improve BCI speller performance towards more practical use for communication.