title: Movement distributions of stroke survivors exhibit distinct patterns that evolve with training.
abstract: BACKGROUND
  While clinical assessments provide tools for characterizing abilities in motor-impaired individuals, concerns remain over their repeatability and reliability. Typical robot-assisted training studies focus on repetition of prescribed actions, yet such movement data provides an incomplete account of abnormal patterns of coordination. Recent studies have shown positive effects from self-directed movement, yet such a training paradigm leads to challenges in how to quantify and interpret performance.
  
  
  METHODS
  With data from chronic stroke survivors (n = 10, practicing for 3 days), we tabulated histograms of the displacement, velocity, and acceleration for planar motion, and examined whether modeling of distributions could reveal changes in available movement patterns. We contrasted these results with scalar measures of the range of motion. We performed linear discriminant analysis (LDA) classification with selected histogram features to compare predictions versus actual subject identifiers. As a basis of comparison, we also present an age-matched control group of healthy individuals (n = 10, practicing for 1 day).
  
  
  RESULTS
  Analysis of range of motion did not show improvement from self-directed movement training for the stroke survivors in this study. However, examination of distributions indicated that increased multivariate normal components were needed to accurately model the patterns of movement after training. Stroke survivors generally exhibited more complex distributions of motor exploration compared to the age-matched control group. Classification using linear discriminant analysis revealed that movement patterns were identifiable by individual. Individuals in the control group were more difficult to identify using classification methods, consistent with the idea that motor deficits contribute significantly to unique movement signatures.
  
  
  CONCLUSIONS
  Distribution analysis revealed individual patterns of abnormal coordination in stroke survivors and changes in these patterns with training. These findings were not apparent from scalar metrics that simply summarized properties of motor exploration. Our results suggest new methods for characterizing motor capabilities, and could provide the basis for powerful tools for designing customized therapy.
authors.affiliation: Sensory Motor Performance Program, Rehabilitation Institute of Chicago, 345 E, Superior Street, Suite 1406, Chicago, IL, 60611, USA. f-huang@northwestern.edu.
authors.forename: Felix C
authors.initials: FC
authors.lastname: Huang
authors.affiliation: Department of Bioengineering, University of Illinois at Chicago, 851 S. Morgan Street, Room 222, Chicago, IL, 60612, USA. pattonj@uic.edu.
authors.forename: James L
authors.initials: JL
authors.lastname: Patton
mesh_terms: D005260:Female; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D000066530:Neurological Rehabilitation / Q000379:methods*; D016059:Range of Motion, Articular / Q000502:physiology*; D015203:Reproducibility of Results; D000071939:Stroke Rehabilitation; D017741:Survivors