title: Decoding motor responses from the EEG during altered states of consciousness induced by propofol.
abstract: OBJECTIVE
  Patients undergoing general anesthesia may awaken and become aware of the surgical procedure. Due to neuromuscular blocking agents, patients could be conscious yet unable to move. Using brain-computer interface (BCI) technology, it may be possible to detect movement attempts from the EEG. However, it is unknown how an anesthetic influences the brain response to motor tasks.
  
  
  METHODS
  We tested the offline classification performance of a movement-based BCI in 12 healthy subjects at two effect-site concentrations of propofol. For each subject a second classifier was trained on the subject's data obtained before sedation, then tested on the data obtained during sedation ('transfer classification').
  
  
  RESULTS
  At concentration 0.5 μg ml(-1), despite an overall propofol EEG effect, the mean single trial classification accuracy was 85% (95% CI 81%-89%), and 83% (79%-88%) for the transfer classification. At 1.0 μg ml(-1), the accuracies were 81% (76%-86%), and 72% (66%-79%), respectively. At the highest propofol concentration for four subjects, unlike the remaining subjects, the movement-related brain response had been largely diminished, and the transfer classification accuracy was not significantly above chance. These subjects showed a slower and more erratic task response, indicating an altered state of consciousness distinct from that of the other subjects.
  
  
  CONCLUSIONS
  The results show the potential of using a BCI to detect intra-operative awareness and justify further development of this paradigm. At the same time, the relationship between motor responses and consciousness and its clinical relevance for intraoperative awareness requires further investigation.
authors: Radboud University Medical Centre, Department of Anaesthesiology, Pain and Palliative Medicine, PO Box 9101, 6500 HB Nijmegen, The Netherlands. Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Montessorilaan 3, 6525 HR Nijmegen, The Netherlands.
authors: Yvonne
authors: Y
authors: Blokland
authors: Jason
authors: J
authors: Farquhar
authors: Jos
authors: J
authors: Lerou
authors: Jo
authors: J
authors: Mourisse
authors: Gert Jan
authors: GJ
authors: Scheffer
authors: Geert-Jan van
authors: GJ
authors: Geffen
authors: Loukianos
authors: L
authors: Spyrou
authors: Jörgen
authors: J
authors: Bruhn
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000293:Adolescent; D000328:Adult; D018686:Anesthetics, Intravenous / Q000008:administration & dosage*; D001364:Awareness / Q000187:drug effects / Q000502:physiology; D062207:Brain-Computer Interfaces; D003243:Consciousness / Q000187:drug effects / Q000502:physiology*; D004569:Electroencephalography / Q000187:drug effects / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D015742:Propofol / Q000008:administration & dosage*; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology*; D055815:Young Adult
chemical_list: D018686:Anesthetics, Intravenous; D015742:Propofol