Can the occipital alpha-phase speed up visual detection through a real-time EEG-based brain-computer interface (BCI)?

Abstract

Electrical brain oscillations reflect fluctuations in neural excitability. Fluctuations in the alpha band (α, 8–12 Hz) in the occipito‐parietal cortex are thought to regulate sensory responses, leading to cyclic variations in visual perception. Inspired by this theory, some past and recent studies have addressed the relationship between α‐phase from extra‐cranial EEG and behavioural responses to visual stimuli in humans. The latest studies have used offline approaches to confirm α‐gated cyclic patterns. However, a particularly relevant implication is the possibility to use this principle online, whereby stimuli are time‐locked to specific α‐phases leading to predictable outcomes in performance. Here, we aimed at providing a proof of concept for such real‐time neurotechnology. Participants performed a speeded response task to visual targets that were presented upon a real‐time estimation of the α‐phase via an EEG closed‐loop brain–computer interface (BCI). According to the theory, we predicted a modulation of reaction times (RTs) along the α‐cycle. Our BCI system achieved reliable trial‐to‐trial phase locking of stimuli to the phase of individual occipito‐parietal α‐oscillations. Yet, the behavioural results did not support a consistent relation between RTs and the phase of the α‐cycle neither at group nor at single participant levels. We must conclude that although the α‐phase might play a role in perceptual decisions from a theoretical perspective, its impact on EEG‐based BCI application appears negligible.