title: A region-based two-step P300-based brain-computer interface for patients with amyotrophic lateral sclerosis.
abstract: OBJECTIVE
  The P300-based brain-computer interface (BCI) is designed to help patients with motor disabilities to control their environment, and it has been used successfully in patients with amyotrophic lateral sclerosis (ALS). However, some ALS patients were unable to use the visual P300-BCI with the conventional row/column presentation. In this study, we evaluated the effect of a newly developed region-based two-step P300 speller, which has a larger flashing area than the conventional visual array.
  
  
  METHODS
  Seven ALS patients and seven age- and sex-matched able-bodied control subjects were required to input hiragana characters using our P300 BCI system. We prepared two types of input procedures, the conventional row/column (RC) speller and the two-step speller, and evaluated their online performance.
  
  
  RESULTS
  The mean online accuracy of the ALS patients was 24% for the RC condition and 55% for the two-step condition. The accuracy of the control subjects was 71% and 83% for the RC and two-step condition, respectively. Accuracy in ALS patients was significantly lower than that in the control subjects, and the new visual stimuli significantly increased accuracy of ALS patients. Using the new speller, two ALS patients showed an initial accuracy sufficient for practical use (>70%). The other two ALS patients, who performed better in the first trial using the new speller, continued to experience the BCI system, and their mean accuracy increased to 92%.
  
  
  CONCLUSIONS
  The two-step procedure for the visual P300 BCI system provided significantly increased accuracy for ALS patients compared with a conventional RC speller.
  
  
  CONCLUSIONS
  The new region-based two-step P300 speller was effective in ALS patients, and the system may be beneficial to expand their range of activities.
authors.affiliation: Systems Neuroscience Section, Department of Rehabilitation for Brain Functions, Research Institute of National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Saitama 359-8555, Japan; Department of Neurological Surgery, Chiba University Graduate School of Medicine, Chiba, Chiba 260-8670, Japan.
authors.forename: Shiro
authors.initials: S
authors.lastname: Ikegami
authors.affiliation: Systems Neuroscience Section, Department of Rehabilitation for Brain Functions, Research Institute of National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Saitama 359-8555, Japan.
authors.forename: Kouji
authors.initials: K
authors.lastname: Takano
authors.affiliation: Department of Neurology, Yoka Hospital, Yabu, Hyogo 667-8555, Japan.
authors.forename: Kiyohiko
authors.initials: K
authors.lastname: Kondo
authors.affiliation: Department of Neurological Surgery, Chiba University Graduate School of Medicine, Chiba, Chiba 260-8670, Japan.
authors.forename: Naokatsu
authors.initials: N
authors.lastname: Saeki
authors.affiliation: Systems Neuroscience Section, Department of Rehabilitation for Brain Functions, Research Institute of National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Saitama 359-8555, Japan; Center for Frontier Medical Engineering, Chiba University, Chiba 263-0022, Japan; Brain Science Inspired Life Support Research Center, The University of Electro-Communications, Tokyo 182-8585, Japan. Electronic address: kansaku-kenji@rehab.go.jp.
authors.forename: Kenji
authors.initials: K
authors.lastname: Kansaku
mesh_terms: D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000503:physiopathology*; D062207:Brain-Computer Interfaces; D004569:Electroencephalography / Q000379:methods; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged
keywords: Amyotrophic lateral sclerosis; BCI; BMI; P300; Visual stimuli