Comparing tactile and visual gaze-independent brain-computer interfaces in patients with amyotrophic lateral sclerosis and healthy users.
OBJECTIVE
Brain-computer interfaces (BCI) tested in patients often are gaze-dependent, while these intended users could possibly lose the ability to focus their gaze. Therefore, a visual and a tactile gaze-independent spelling system were investigated.


METHODS
Five patients with amyotrophic lateral sclerosis (ALS) tested a visual Hex-o-Spell and a tactile speller. Six healthy participants were also included, mainly to evaluate the tactile stimulators.


RESULTS
A significant attentional modulation was seen in the P300 for the Hex-o-Spell and in the N2 for the tactile speller. Average on-line classification performance for selecting a step in the speller was above chance level (17%) for both spellers. However, average performance was higher for the Hex-o-Spell (88% and 85% for healthy participants and patients, respectively) than for the tactile speller (56% and 53%, respectively). Likewise, bitrates were higher for the Hex-o-Spell compared with the tactile speller, and in the subjective usability a preference for the Hex-o-Spell was found.


CONCLUSIONS
The Hex-o-Spell outperformed the tactile speller in classification performance, bit rate and subjective usability.


CONCLUSIONS
This is the first study showing the possible use of tactile and visual gaze-independent BCI spelling systems by ALS patients with mild to moderate disabilities.
Sint Maartenskliniek Nijmegen, Research Department, The Netherlands; Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, The Netherlands. Electronic address: m.severens@gmail.com.
M
M
Severens
Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, The Netherlands.
M
M
Van der Waal
Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, The Netherlands.
J
J
Farquhar
Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, The Netherlands.
P
P
Desain
D000328:Adult; D000690:Amyotrophic Lateral Sclerosis / Q000503:physiopathology*; D001288:Attention / Q000502:physiology; D062207:Brain-Computer Interfaces; D006233:Persons with Disabilities; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014110:Touch / Q000502:physiology*; D014785:Vision, Ocular / Q000502:physiology*; D055815:Young Adult
ALS; Attention; BCI; EEG; Somatosensory evoked potentials; Visual evoked potentials