Performance of a tactile P300 speller for healthy people and severely disabled patients

Abstract

P300 based Brain-Computer Interfaces (BCIs) for communication are well known since many years. Most of them use visual stimuli to elicit evoked potentials because it is easy to integrate a high number of different classes into the paradigm. Nevertheless, a BCI that depends on visual stimuli is sometimes not feasible due to the presence of visual impairment in patients with severe brain injuries. In this case, it could be possible to use auditory or somatosensory stimulation. In this publication a vibrotactile P300 based BCI is introduced. Two different approaches were tested: a first approach using two stimulators and a second one that utilizes three stimulators for emitting the stimuli. The two paradigms were tested on 16 users: A group of ten healthy users and a second group comprising of 6 patients suffering Locked-In Syndrome. The control accuracy was calculated for both groups and both approaches, proving the feasibility of the device, not only for healthy people but also in severely disabled patients. In a second step we evaluated the influence of the number of stimuli on the accuracy. It was shown that in many cases the maximum accuracy was already reached with a small number of stimuli, this could be used in future tests to speed up the Information transfer rate.

Complete Locked-in and Locked-in Patients: Command Following Assessment and Communication with Vibro-Tactile P300 and Motor Imagery Brain-Computer Interface Tools

“…In this study, the patients were instructed to actively count the target (deviant) stimuli to produce an active P300 response that is normally higher than a passive P300 response. Also, the VT3 paradigm exhibits training effects, presumably because it is slightly harder to learn (Ortner et al, 2013 ). Fourth, the literature has shown that some training is required to attain good accuracy with MI BCIs, and subjects in this study were untrained.…”

“…Since EEG BCIs can assess mental activity and even enable communication without requiring movement, some groups have extended EEG BCIs to assessment and communication for persons with DOC (Risetti et al, 2013 ; Guger et al, 2016b ; Ortner et al, in press ). The EEG-based mindBEAGLE BCI system was recently developed to provide a convenient, fast, and practical platform for cognitive assessment of command following and communication system for such patients (Ortner et al, 2013 , in press ; Guger et al, 2016b ). This system relies on P300 and motor imagery BCIs and a step-by-step explanation is given in (Ortner et al, in press ).…”

EEG-based vibrotactile evoked brain-computer interfaces system: A systematic review

“…Surprisingly, only around one-fifth of EVE-BCI studies were carried out for patients. These patients suffered from multiple levels of motor functioning loses caused by different diseases including the unresponsive wakefulness syndrome (UWS) [ 8 , 79 ], disorder of consciousness (DOC) [ 9 , 49 , 61 , 63 , 70 ], amyotrophic lateral sclerosis (ALS) [ 54 , 57 , 87 , 89 , 103 ], locked-in syndrome (LIS) [ 58 , 63 , 70 , 78 ], stroke [ 94 ], and minimally conscious state (MCS) [ 86 ]. On the other hand, most studies (83.54% of cases) alternatively focused on healthy subjects covering adults of all ages, including young people, the middle-aged, and elders.…”

Trends in BCI Research I: Brain-Computer Interfaces for Assessment of Patients with Locked-in Syndrome or Disorders of Consciousness

“…In the VT3 approach, one tactor is mounted on the left hand (10% of stimuli), one tactor is mounted on the right hand (10% of stimuli) and one tactor is mounted on the spine or leg (80% of the stimuli) [5,6]. Now the patient can count the stimuli on the left hand to say YES and can say NO by counting right hand stimuli.…”