Comparison of a row-column speller vs. a novel lateral single-character speller: Assessment of BCI for severe motor disabled patients

ObjectiveNon-invasive brain–computer interface (BCI) based on electroencephalography (EEG) offers a new communication channel for people suffering from severe motor disorders. This paper presents a novel P300-based speller called lateral single-character (LSC). The LSC performance is compared to that of the standard row-column (RC) speller.MethodsWe developed LSC, a single-character paradigm comprising all letters of the alphabet following an event strategy that significantly reduces the time for symbol selection, and explores the intrinsic hemispheric asymmetries in visual perception to improve the performance of the BCI. RC and LSC paradigms were tested by 10 able-bodied participants, seven participants with amyotrophic lateral sclerosis (ALS), five participants with cerebral palsy (CP), one participant with Duchenne muscular dystrophy (DMD), and one participant with spinal cord injury (SCI).ResultsThe averaged results, taking into account all participants who were able to control the BCI online, were significantly higher for LSC, 26.11 bit/min and 89.90% accuracy, than for RC, 21.91 bit/min and 88.36% accuracy. The two paradigms produced different waveforms and the signal-to-noise ratio was significantly higher for LSC. Finally, the novel LSC also showed new discriminative features.ConclusionsThe results suggest that LSC is an effective alternative to RC, and that LSC still has a margin for potential improvement in bit rate and accuracy.SignificanceThe high bit rates and accuracy of LSC are a step forward for the effective use of BCI in clinical applications.

► We propose a novel P300-based lateral single-character (LSC) speller, that explores layout, event strategy, and hemispheric asymmetries in visual perception to improve the performance of brain–computer interfaces.
► The online performance of the LSC paradigm is compared to that of the standard row-column (RC) paradigm.
► The paradigms are tested by individuals with neuromuscular disorders (amyotrophic lateral sclerosis, cerebral palsy, Duchenne muscular dystrophy, and spinal cord injury).