A gaze-independent audiovisual brain-computer Interface for detecting awareness of patients with disorders of consciousness

Abstract

BackgroundCurrently, it is challenging to detect the awareness of patients who suffer disorders of consciousness (DOC). Brain-computer interfaces (BCIs), which do not depend on the behavioral response of patients, may serve for detecting the awareness in patients with DOC. However, we must develop effective BCIs for these patients because their ability to use BCIs does not as good as healthy users.MethodsBecause patients with DOC generally do not exhibit eye movements, a gaze-independent audiovisual BCI is put forward in the study where semantically congruent and incongruent audiovisual number stimuli were sequentially presented to evoke event-related potentials (ERPs). Subjects were required to pay attention to congruent audiovisual stimuli (target) and ignore the incongruent audiovisual stimuli (non-target). The BCI system was evaluated by analyzing online and offline data from 10 healthy subjects followed by being applied to online awareness detection in 8 patients with DOC.ResultsAccording to the results on healthy subjects, the audiovisual BCI system outperformed the corresponding auditory-only and visual-only systems. Multiple ERP components, including the P300, N400 and late positive complex (LPC), were observed using the audiovisual system, strengthening different brain responses to target stimuli and non-target stimuli. The results revealed the abilities of three of eight patients to follow commands and recognize numbers.ConclusionsThis gaze-independent audiovisual BCI system represents a useful auxiliary bedside tool to detect the awareness of patients with DOC.

Estimating statistical power for event‐related potential studies using the late positive potential

“…The affective modulation of the LPP is not influenced by the images' perceptual composition (Bradley, Hamby, Löw, & Lang, ; Codispoti, De Cesarei, & Ferrari, ; De Cesarei & Codispoti, ), exposure time (Codispoti et al, ), or repetition (Ferrari, Codispoti, & Bradley, ). These characteristics lead researchers to consider the LPP a robust index of motivational relevance (Lang & Bradley, ) and a useful tool for investigating affective processes in clinical populations, such as individuals affected by neurological disorders (Xie et al, ), post‐traumatic stress disorder (PTSD) and other anxiety disorders (Fitzgerald et al, ; MacNamara, Jackson, Fitzgerald, Hajcak, & Phan, ; Zhang et al, ), depression (Weinberg, Perlman, Kotov, & Hajcak, ), drug abuse (Dunning et al, ; Versace et al, ), anhedonia (Weinberg et al, ), psychopathy (Ellis, Schroder, Patrick, & Moser, ), and schizophrenia (Culbreth, Foti, Barch, Hajcak, & Kotov, ; Strandburg et al, ).…”

A Novel Audiovisual P300-Speller Paradigm Based on Cross-Modal Spatial and Semantic Congruence

“…The third ERP component with a significant difference was between 700 and 780 ms in the frontal and central areas, and it might be a late positive component (LPC) related to the semantically congruent stimuli. Xie et al (2018) also observed an enhanced LPC amplitude induced by audiovisual stimuli compared with a unimodal stimulus in the semantically congruent condition at electrodes Fz, Cz, and Pz between 700 and 900 ms. The LPC component has been often observed in studies about semantics and in tasks such as memorizing congruous or incongruous auditory sentences (McCallum et al, 1984), memorizing word lists (Martin and Chao, 2001), and making decisions on congruency (Kounios and Holcomb, 1992).…”

Behind the Scenes of Noninvasive Brain–Computer Interfaces: A Review of Electroencephalography Signals, How They Are Recorded, and Why They Matter

“…As the N400 is primarily produced by incongruency, in the absence of a motor response, future research may wish to explore the N400 and incongruency-based paradigms as the foundation for gaze-independent audiovisual BCI systems (e.g., Xie et al, 2018). However, currently in the field of BCI, the N400 is largely discussed in the context of supporting improved outcomes for P300-based BCI devices, and N400 elicitation directly influences how the visual displays for gridbased P300 BCI devices are designed.…”