The auditory P300-based single-switch brain–computer interface: Paradigm transition from healthy subjects to minimally conscious patients

Abstract

Objective: Within this work an auditory P300 brain-computer interface (BCI) based on tone stream segregation, which allows for binary decisions, was developed and evaluated. Materials and methods: Two tone streams consisting of short beep tones with infrequently appearing deviant tones at random positions were used as stimuli. This paradigm was evaluated in 10 healthy subjects and applied to 12 patients in a minimally conscious state (MCS) at clinics in Graz, Würzburg, Rome, and Liège. A stepwise linear discriminant analysis (SWLDA) classifier with 10 × 10 cross-validation was used to detect the presence of any P300 and to investigate attentional modulation of the P300 amplitude. Results:The results for healthy subjects were promising and most classification results were better than random. However, for MCS patients only a small number of classification results were above chance level and none of the results were sufficient for communication purposes. Nevertheless, signs of consciousness were detected in most patients, not on a single-trial basis, but after averaging of corresponding data segments and computing significant differences. These significant results, however, strongly varied across sessions and conditions. Conclusion: This work shows the transition of a paradigm from healthy subjects to MCS patients. Promising results with healthy subjects are, however, no guarantee of good results with patients. Therefore, more investigations are required before any definite conclusions about the usability of this paradigm for MCS patients can be drawn. Nevertheless, this paradigm might offer an opportunity to support bedside clinical assessment of MCS patients and eventually, to provide them with a means of communication.

Information processing in patients in vegetative and minimally conscious states

“…While complex tones were shown to be superior to simple sines , other stimuli, such as emotional interjections (Neumann and Kotchoubey, 2004), or different stimulus properties might give different, but not necessarily better (Pokorny et al, 2013) results. An important argument concerns the number of stimuli (60 odd, 420 frequent tones) used in our study.…”

Interfaces cerveau-ordinateur,locked-in syndromeet troubles de la conscience

“…Différentes réponses cérébrales peuvent être détectées par une interface cerveau-ordinateur utilisant l'EEG (EEG-BCI). Parmi les réponses électrophysiologiques les plus utilisées, qui sont les potentiels corticaux lents 1 [15], les rythmes sensori-moteurs 2 [16], les potentiels évoqués 3 P300 4 [17] et les potentiels évoqués visuels steady-state (steady-state visually evoked potential, SSVEP) 5 [18,19], deux ont été évaluées comme outil de détection d'une réponse à une commande dans le contexte des troubles de la conscience. Il s'agit des rythmes sensori-moteurs, qui reflétent un changement de l'activité cérébrale dans les régions motrices suite à l'imagination d'un mouvement, et la P300, qui révèle une réponse évoquée par la présentation d'un stimulus inattendu, au sein de stimulus fréquents.…”

User-centred design in brain–computer interface research and development

“…Despite the difficulties, a considerable number of studies, although with low sample sizes, were conducted to fulfil exactly this request and refer explicitly to the UCD [11][12][13][14][15][16][17][18][19]. A few more were also conducted with patient end-users as a focus but without referring to the UCD [4,[20][21][22]. The late 2014 and 2015 papers may have been not available when Nijboer's manuscript went in press, but the earlier ones were.…”