Novel sequential BCI speller based on ERPs and event-related slow cortical potentials

Area of Science:

• Neuroscience
• Biomedical Engineering
• Human-Computer Interaction

Background:

• The P300 oddball paradigm has been the cornerstone of brain-computer interface (BCI) spellers for decades, but performance improvements have been incremental.
• Farwell and Donchin proposed a periodic stimulation pattern as a potential alternative, predicting it could elicit contingent negative variation (CNV) and enhance performance, though this remained uninvestigated.

Purpose of the Study:

• To investigate the viability of a periodic stimulation pattern as an alternative to the oddball paradigm in BCI spellers.
• To compare the performance of a periodic BCI speller with the traditional matrix speller.

Main Methods:

• A novel BCI speller utilizing a circular arrangement of 36 letters with sequential highlighting was developed.
• The periodic stimulation protocol was compared against the original matrix speller at two different stimulus presentation rates.

Main Results:

• The periodic speller successfully elicited clear P300s, contingent negative variations (CNVs), and other slow cortical potentials (SCPs).
• At a higher stimulation rate, the periodic speller demonstrated significantly superior performance metrics, including AUC, classification accuracy, and information transfer rate (ITR), compared to the Donchin speller.

Conclusions:

• Periodic stimulation is a viable alternative to the oddball paradigm for BCI spellers, capable of eliciting both P300s and various event-related SCPs.
• This approach offers significant performance improvements and opens new avenues for developing more efficient communication systems for individuals with severe motor impairments by combining event-related potentials with naturally-triggered SCPs.