title: Movement planning and online control in multiple sclerosis: assessment using a Fitts law reciprocal aiming task.
abstract: OBJECTIVE
  We sought to quantify subtle changes in motor control in multiple sclerosis (MS) using a Fitts law reciprocal aiming task presented on a computer touchscreen.
  
  
  BACKGROUND
  Upper-limb motor control is impaired in MS. However, many commonly used motor assessments do not detect subtle changes in motor function or differentiate between aspects of movement such as planning and online control. Fitts law states that movement time varies as a function of task difficulty, with smaller targets and greater distances making the task more difficult.
  
  
  METHODS
  We gave a Fitts aiming task to 22 patients with MS and 22 matched controls. We manipulated movement difficulty by changing the targets' size and distance apart.
  
  
  RESULTS
  The patients spent a significantly longer time than the controls stationary in each target before starting the next movement, and had a lower peak velocity, suggesting deficits in movement planning. The patients also spent longer in the deceleration phase of each movement, indicating deficits in the online control of movement.
  
  
  CONCLUSIONS
  The computerized Fitts task allows quick, easy, and sensitive measurement of subtle aspects of movement. This task should be useful in clinical and research settings for assessing MS motor symptoms, disease progression, and treatment efficacy.
authors.affiliation: *Experimental Neuropsychology Research Unit †Ocular Motor Research Laboratory ∥Centre for Developmental Psychiatry and Psychology, School of Psychological Sciences, Monash University, Clayton, Victoria, Australia ‡Department of Neurology, Royal Melbourne Hospital, Parkville, Victoria, Australia §Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia.
authors.forename: Anne-Marie S
authors.initials: AM
authors.lastname: Ternes
authors.forename: Joanne
authors.initials: J
authors.lastname: Fielding
authors.forename: Louise A
authors.initials: LA
authors.lastname: Corben
authors.forename: Owen B
authors.initials: OB
authors.lastname: White
authors.forename: John L
authors.initials: JL
authors.lastname: Bradshaw
authors.forename: Darren R
authors.initials: DR
authors.lastname: Hocking
authors.forename: Nellie
authors.initials: N
authors.lastname: Georgiou-Karistianis
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003198:Computer Simulation; D018450:Disease Progression; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D009068:Movement; D009103:Multiple Sclerosis / Q000503:physiopathology* / Q000523:psychology*; D009483:Neuropsychological Tests; D011597:Psychomotor Performance