title: Hybrid brain-computer interface and functional electrical stimulation for sensorimotor training in participants with tetraplegia: a proof-of-concept study.
abstract: OBJECTIVE
  Impaired hand function decreases quality of life in persons with tetraplegia. We tested functional electrical stimulation (FES) controlled by a hybrid brain-computer interface (BCI) for improving hand function in participants with tetraplegia.
  
  
  METHODS
  Two participants with subacute tetraplegia (participant 1: C5 Brown-Sequard syndrome, participant 2: complete C5 lesion) took part in this proof-of-concept study. The goal was to determine whether the BCI system could drive the FES device by accurately classifying participants' intent (open or close the hand). Participants 1 and 2 received 10 sessions and 4 sessions of BCI-FES, respectively. A novel time-switch BCI strategy based on motor imagery was used to activate the FES. In one session, we tested a hybrid BCI-FES based on 2 spontaneously generated brain rhythms: a sensory-motor rhythm during motor imagery to activate a stimulator and occipital alpha rhythms to deactivate the stimulator. Participants received BCI-FES therapy 2 to 3 times a week in addition to conventional therapy. Imagery ability and muscle strength were measured before and after treatment.
  
  
  RESULTS
  Visual feedback was associated with a 4-fold increase of brain response during motor imagery in both participants. For participant 1, classification accuracy (open/closed) for motor imagery-based BCI was 83.5% (left hand) and 83.8% (right hand); participant 2 had a classification accuracy of 83.8% for the right hand. Participant 1 had moderate improvement in muscle strength, while there was no change for participant 2.
  
  
  CONCLUSIONS
  We demonstrated feasibility of BCI-FES, using 2 naturally generated brain rhythms. Studies on a larger number of participants are needed to separate the effects of BCI training from effects of conventional therapy.Video Abstract available. (see Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A84) for more insights from the authors.
authors.affiliation: Biomedical Engineering, School of Engineering, University of Glasgow (A.V.), and Queen Elizabeth National Spinal Injuries Unit, Southern General Hospital (L.W., D.B.A), Glasgow, the United Kingdom.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Vučković
authors.forename: Leslie
authors.initials: L
authors.lastname: Wallace
authors.forename: David B
authors.initials: DB
authors.lastname: Allan
mesh_terms: D000328:Adult; D062207:Brain-Computer Interfaces; D004599:Electric Stimulation Therapy; D004569:Electroencephalography; D006225:Hand / Q000503:physiopathology*; D006801:Humans; D007092:Imagination / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology*; D011782:Quadriplegia / Q000503:physiopathology / Q000534:rehabilitation*; D011788:Quality of Life