title: A brain-computer interface with vibrotactile biofeedback for haptic information.
abstract: BACKGROUND
  It has been suggested that Brain-Computer Interfaces (BCI) may one day be suitable for controlling a neuroprosthesis. For closed-loop operation of BCI, a tactile feedback channel that is compatible with neuroprosthetic applications is desired. Operation of an EEG-based BCI using only vibrotactile feedback, a commonly used method to convey haptic senses of contact and pressure, is demonstrated with a high level of accuracy.
  
  
  METHODS
  A Mu-rhythm based BCI using a motor imagery paradigm was used to control the position of a virtual cursor. The cursor position was shown visually as well as transmitted haptically by modulating the intensity of a vibrotactile stimulus to the upper limb. A total of six subjects operated the BCI in a two-stage targeting task, receiving only vibrotactile biofeedback of performance. The location of the vibration was also systematically varied between the left and right arms to investigate location-dependent effects on performance.
  
  
  CONCLUSIONS
  Subjects are able to control the BCI using only vibrotactile feedback with an average accuracy of 56% and as high as 72%. These accuracies are significantly higher than the 15% predicted by random chance if the subject had no voluntary control of their Mu-rhythm. The results of this study demonstrate that vibrotactile feedback is an effective biofeedback modality to operate a BCI using motor imagery. In addition, the study shows that placement of the vibrotactile stimulation on the biceps ipsilateral or contralateral to the motor imagery introduces a significant bias in the BCI accuracy. This bias is consistent with a drop in performance generated by stimulation of the contralateral limb. Users demonstrated the capability to overcome this bias with training.
authors.affiliation: Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, MD, USA. ani.chatterjee@gmail.com
authors.forename: Aniruddha
authors.initials: A
authors.lastname: Chatterjee
authors.forename: Vikram
authors.initials: V
authors.lastname: Aggarwal
authors.forename: Ander
authors.initials: A
authors.lastname: Ramos
authors.forename: Soumyadipta
authors.initials: S
authors.lastname: Acharya
authors.forename: Nitish V
authors.initials: NV
authors.lastname: Thakor
mesh_terms: D000328:Adult; D001676:Biofeedback, Psychology / Q000379:methods*; D001921:Brain / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005260:Female; D006801:Humans; D007092:Imagination / Q000502:physiology*; D008297:Male; D013647:Task Performance and Analysis; D014110:Touch / Q000502:physiology*; D014584:User-Computer Interface; D014732:Vibration