title: Infantile nystagmus syndrome is associated with inefficiency of goal-directed hand movements.
abstract: OBJECTIVE
  The effect of infantile nystagmus syndrome (INS) on the efficiency of goal-directed hand movements was examined.
  
  
  METHODS
  We recruited 37 children with INS and 65 control subjects with normal vision, aged 4 to 8 years. Participants performed horizontally-oriented, goal-directed cylinder displacements as if they displaced a low-vision aid. The first 10 movements of 20 back-and-forth displacements in a trial were performed between two visually presented target areas, and the second 10 between remembered target locations (not visible). Motor performance was examined in terms of movement time, endpoint accuracy, and a harmonicity index reflecting energetic efficiency.
  
  
  RESULTS
  Compared to the control group, the children with INS performed the cylinder displacements more slowly (using more time), less accurately (specifically in small-amplitude movements), and with less harmonic acceleration profiles. Their poor visual acuity proved to correlate with slower and less accurate movements, but did not correlate with harmonicity. When moving between remembered target locations, the performance of children with INS was less accurate than that of the children with normal vision. In both groups, movement speed and harmonicity increased with age to a similar extent.
  
  
  CONCLUSIONS
  Collectively, the findings suggest that, in addition to the visuospatial homing-in problems associated with the syndrome, INS is associated with inefficiency of goal-directed hand movements. ( http://www.trialregister.nl number, NTR2380.).
authors.affiliation: Behavioural Science Institute, Radboud University, Nijmegen, The Netherlands Bartiméus, Institute for the Visually Impaired, Zeist, The Netherlands.
authors.forename: Joyce
authors.initials: J
authors.lastname: Liebrand-Schurink
authors.affiliation: Bartiméus, Institute for the Visually Impaired, Zeist, The Netherlands Department of Developmental Psychology, University of Groningen, Groningen, The Netherlands.
authors.forename: Ralf F A
authors.initials: RF
authors.lastname: Cox
authors.affiliation: VU Medical Centre Amsterdam, Amsterdam, The Netherlands.
authors.forename: Ger H M B
authors.initials: GH
authors.lastname: van Rens
authors.affiliation: Behavioural Science Institute, Radboud University, Nijmegen, The Netherlands.
authors.forename: Antonius H N
authors.initials: AH
authors.lastname: Cillessen
authors.affiliation: Department Cognitive Neuroscience, Donders Institute for Brain, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Ruud G J
authors.initials: RG
authors.lastname: Meulenbroek
authors.affiliation: Bartiméus, Institute for the Visually Impaired, Zeist, The Netherlands Department Cognitive Neuroscience, Donders Institute for Brain, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: F Nienke
authors.initials: FN
authors.lastname: Boonstra
mesh_terms: D001132:Arm / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D020417:Nystagmus, Congenital / Q000503:physiopathology*; D011597:Psychomotor Performance / Q000502:physiology*; D013577:Syndrome; D014792:Visual Acuity
keywords: children; goal-directed hand movements; infantile nystagmus syndrome; sensorimotor development