@article{KaethnerKueblerHalder2015,
  author    = {K{\"a}thner, Ivo and K{\"u}bler, Andrea and Halder, Sebastian},
  title     = {Rapid P300 brain-computer interface communication with a head-mounted display},
  series = {Frontiers in Neuroscience},
  volume    = {9},
  journal   = {Frontiers in Neuroscience},
  number    = {207},
  doi       = {10.3389/fnins.2015.00207},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-148520},
  year      = {2015},
  abstract  = {Visual ERP (P300) based brain-computer interfaces (BCIs) allow for fast and reliable spelling and are intended as a muscle-independent communication channel for people with severe paralysis. However, they require the presentation of visual stimuli in the field of view of the user. A head-mounted display could allow convenient presentation of visual stimuli in situations, where mounting a conventional monitor might be difficult or not feasible (e.g., at a patient's bedside). To explore if similar accuracies can be achieved with a virtual reality (VR) headset compared to a conventional flat screen monitor, we conducted an experiment with 18 healthy participants. We also evaluated it with a person in the locked-in state (LIS) to verify that usage of the headset is possible for a severely paralyzed person. Healthy participants performed online spelling with three different display methods. In one condition a 5 x 5 letter matrix was presented on a conventional 22 inch TFT monitor. Two configurations of the VR headset were tested. In the first (glasses A), the same 5 x 5 matrix filled the field of view of the user. In the second (glasses B), single letters of the matrix filled the field of view of the user. The participant in the LIS tested the VR headset on three different occasions (glasses A condition only). For healthy participants, average online spelling accuracies were 94\% (15.5 bits/min) using three flash sequences for spelling with the monitor and glasses A and 96\% (16.2 bits/min) with glasses B. In one session, the participant in the LIS reached an online spelling accuracy of 100\% (10 bits/min) using the glasses A condition. We also demonstrated that spelling with one flash sequence is possible with the VR headset for healthy users (mean: 32.1 bits/min, maximum reached by one user: 71.89 bits/min at 100\% accuracy). We conclude that the VR headset allows for rapid P300 BCI communication in healthy users and may be a suitable display option for severely paralyzed persons.},
  language  = {en}
}
@article{MuenssingerHalderKleihetal.2010,
  author    = {M{\"u}nßinger, Jana I. and Halder, Sebastian and Kleih, Sonja C. and Furdea, Adrian and Raco, Valerio and H{\"o}sle, Adi and K{\"u}bler, Andrea},
  title     = {Brain Painting: first evaluation of a new brain-computer interface application with ALS-patients and healthy volunteers},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68168},
  year      = {2010},
  abstract  = {Brain-computer interfaces (BCIs) enable paralyzed patients to communicate; however, up to date, no creative expression was possible. The current study investigated the accuracy and user-friendliness of P300-Brain Painting, a new BCI application developed to paint pictures using brain activity only. Two different versions of the P300-Brain Painting application were tested: A colored matrix tested by a group of ALS-patients (n = 3) and healthy participants (n = 10), and a black and white matrix tested by healthy participants (n = 10). The three ALS-patients achieved high accuracies; two of them reaching above 89\% accuracy. In healthy subjects, a comparison between the P300-Brain Painting application (colored matrix) and the P300-Spelling application revealed significantly lower accuracy and P300 amplitudes for the P300-Brain Painting application. This drop in accuracy and P300 amplitudes was not found when comparing the P300-Spelling application to an adapted, black and white matrix of the P300-Brain Painting application. By employing a black and white matrix, the accuracy of the P300-Brain Painting application was significantly enhanced and reached the accuracy of the P300-Spelling application. ALS-patients greatly enjoyed P300-Brain Painting and were able to use the application with the same accuracy as healthy subjects. P300-Brain Painting enables paralyzed patients to express themselves creatively and to participate in the prolific society through exhibitions.},
  subject      = {Psychologie},
  language  = {en}
}
@article{HalderTakanoOraetal.2016,
  author    = {Halder, Sebastian and Takano, Kouji and Ora, Hiroki and Onishi, Akinari and Utsumi, Kota and Kansaku, Kenji},
  title     = {An Evaluation of Training with an Auditory P300 Brain-Computer Interface for the Japanese Hiragana Syllabary},
  series = {Frontiers in Neuroscience},
  volume    = {10},
  journal   = {Frontiers in Neuroscience},
  number    = {446},
  doi       = {10.3389/fnins.2016.00446},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-165465},
  year      = {2016},
  abstract  = {Gaze-independent brain-computer interfaces (BCIs) are a possible communication channel for persons with paralysis. We investigated if it is possible to use auditory stimuli to create a BCI for the Japanese Hiragana syllabary, which has 46 Hiragana characters. Additionally, we investigated if training has an effect on accuracy despite the high amount of different stimuli involved. Able-bodied participants (N = 6) were asked to select 25 syllables (out of fifty possible choices) using a two step procedure: First the consonant (ten choices) and then the vowel (five choices). This was repeated on 3 separate days. Additionally, a person with spinal cord injury (SCI) participated in the experiment. Four out of six healthy participants reached Hiragana syllable accuracies above 70\% and the information transfer rate increased from 1.7 bits/min in the first session to 3.2 bits/min in the third session. The accuracy of the participant with SCI increased from 12\% (0.2 bits/min) to 56\% (2 bits/min) in session three. Reliable selections from a 10 × 5 matrix using auditory stimuli were possible and performance is increased by training. We were able to show that auditory P300 BCIs can be used for communication with up to fifty symbols. This enables the use of the technology of auditory P300 BCIs with a variety of applications.},
  language  = {en}
}
@article{SimonKaethnerRufetal.2015,
  author    = {Simon, Nadine and K{\"a}thner, Ivo and Ruf, Carolin A. and Pasqualotto, Emanuele and K{\"u}bler, Andrea and Halder, Sebastian},
  title     = {An auditory multiclass brain-computer interface with natural stimuli: Usability evaluation with healthy participants and a motor impaired end user},
  series = {Frontiers in Human Neuroscience},
  volume    = {8},
  journal   = {Frontiers in Human Neuroscience},
  number    = {1039},
  doi       = {10.3389/fnhum.2014.01039},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-126450},
  year      = {2015},
  abstract  = {Brain-computer interfaces (BCIs) can serve as muscle independent communication aids. Persons, who are unable to control their eye muscles (e.g., in the completely locked-in state) or have severe visual impairments for other reasons, need BCI systems that do not rely on the visual modality. For this reason, BCIs that employ auditory stimuli were suggested. In this study, a multiclass BCI spelling system was implemented that uses animal voices with directional cues to code rows and columns of a letter matrix. To reveal possible training effects with the system, 11 healthy participants performed spelling tasks on 2 consecutive days. In a second step, the system was tested by a participant with amyotrophic lateral sclerosis (ALS) in two sessions. In the first session, healthy participants spelled with an average accuracy of 76\% (3.29 bits/min) that increased to 90\% (4.23 bits/min) on the second day. Spelling accuracy by the participant with ALS was 20\% in the first and 47\% in the second session. The results indicate a strong training effect for both the healthy participants and the participant with ALS. While healthy participants reached high accuracies in the first session and second session, accuracies for the participant with ALS were not sufficient for satisfactory communication in both sessions. More training sessions might be needed to improve spelling accuracies. The study demonstrated the feasibility of the auditory BCI with healthy users and stresses the importance of training with auditory multiclass BCIs, especially for potential end-users of BCI with disease.},
  language  = {en}
}