title: Brain-computer interfaces and communication in paralysis: extinction of goal directed thinking in completely paralysed patients?
abstract: OBJECTIVE
  To investigate the relationship between physical impairment and brain-computer interface (BCI) performance.
  
  
  METHODS
  We present a meta-analysis of 29 patients with amyotrophic lateral sclerosis and six patients with other severe neurological diseases in different stages of physical impairment who were trained with a BCI. In most cases voluntary regulation of slow cortical potentials has been used as input signal for BCI-control. More recently sensorimotor rhythms and the P300 event-related brain potential were recorded.
  
  
  RESULTS
  A strong correlation has been found between physical impairment and BCI performance, indicating that performance worsens as impairment increases. Seven patients were in the complete locked-in state (CLIS) with no communication possible. After removal of these patients from the analysis, the relationship between physical impairment and BCI performance disappeared. The lack of a relation between physical impairment and BCI performance was confirmed when adding BCI data of patients from other BCI research groups.
  
  
  CONCLUSIONS
  Basic communication (yes/no) was not restored in any of the CLIS patients with a BCI. Whether locked-in patients can transfer learned brain control to the CLIS remains an open empirical question.
  
  
  CONCLUSIONS
  Voluntary brain regulation for communication is possible in all stages of paralysis except the CLIS.
authors.affiliation: Clinical and Health Psychology Research Centre, School of Human and Life Sciences, Roehampton University, Whitelands College, Holybourne Avenue, London SW15 4JD, UK. a.kuebler@roehampton.ac.uk
authors.forename: A
authors.initials: A
authors.lastname: Kübler
authors.forename: N
authors.initials: N
authors.lastname: Birbaumer
mesh_terms: D000328:Adult; D000368:Aged; D001927:Brain Diseases / Q000150:complications; D003143:Communication Devices for People with Disabilities; D003199:Computer Systems; D004569:Electroencephalography / Q000379:methods; D018913:Event-Related Potentials, P300 / Q000502:physiology; D005260:Female; D006040:Goals; D006801:Humans; D008297:Male; D015201:Meta-Analysis as Topic; D008875:Middle Aged; D010243:Paralysis / Q000209:etiology / Q000534:rehabilitation*; D010507:Periodicity; D013850:Thinking / Q000502:physiology*; D014584:User-Computer Interface