title: Pattern classification of volitional functional magnetic resonance imaging responses in patients with severe brain injury.
abstract: BACKGROUND
  Recent neuroimaging investigations have explored the use of mental imagery tasks as proxies for an overt motor response, in which patients are asked to imagine performing a task, such as "Imagine yourself swimming."
  
  
  OBJECTIVE
  To detect covert volitional brain activity in patients with severe brain injury using pattern classification of the blood oxygenation level-dependent (BOLD) response during mental imagery and to compare these results with those of a univariate functional magnetic resonance imaging analysis.
  
  
  METHODS
  Case-control study.
  
  
  METHODS
  Academic research.
  
  
  METHODS
  Experiments were performed in 8 healthy control subjects and in 5 patients with severe brain injury. The patients with severe brain injury constituted a convenience sample.
  
  
  METHODS
  Functional magnetic resonance imaging data were acquired as the patients were asked to follow commands or to answer questions using motor imagery as a proxy response.
  
  
  RESULTS
  In the controls, the responses were accurately classified. In the patient group, the responses of 3 of 5 patients were correctly classified. The remaining 2 patients showed no significant BOLD response in a standard univariate analysis, suggesting that they did not perform the task. In addition, we showed that a classifier trained on command-following data can be used to evaluate a later communication run. This technique was used to successfully disambiguate 2 potential BOLD responses to a single question.
  
  
  CONCLUSIONS
  Pattern classification in functional magnetic resonance imaging is a promising technique for advancing the understanding of volitional brain responses in patients with severe brain injury and may serve as a powerful complement to traditional general linear model-based univariate analysis methods.
authors.affiliation: Department of Neuroscience, Weill Cornell Graduate School of Medical Sciences, New York, NY 10021, USA.
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Bardin
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Schiff
authors.forename: Henning U
authors.initials: HU
authors.lastname: Voss
mesh_terms: D000328:Adult; D001519:Behavior; D001930:Brain Injuries / Q000473:pathology* / Q000523:psychology; D016022:Case-Control Studies; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007092:Imagination / Q000502:physiology; D008279:Magnetic Resonance Imaging / Q000145:classification* / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000473:pathology; D010100:Oxygen / Q000097:blood; D018458:Persistent Vegetative State / Q000209:etiology / Q000473:pathology; D011782:Quadriplegia / Q000209:etiology / Q000473:pathology; D055815:Young Adult
chemical_list: D010100:Oxygen