title: Alteration of postural responses to visual field motion in mild traumatic brain injury.
abstract: OBJECTIVE
  Balance deficits in individuals experiencing mild traumatic brain injury have been documented in numerous recent studies. However, long-lasting balance deficits and specific mechanisms causing these deficits have not been systematically examined. This article aimed to present empirical evidence showing destabilizing effects of visual field motion in concussed individuals up to 30 days postinjury.
  
  
  METHODS
  Sixty student athletes participated in the pilot (n = 12) and major experiments (n = 48) before injury. Eight of these 48 subjects who experienced mild traumatic brain injury in athletic events were tested again on Days 3, 10, and 30 after the incident. Postural responses to visual field motion were recorded using a virtual reality environment in conjunction with balance (AMTI force plate) and motion tracking (Flock of Birds) technologies.
  
  
  RESULTS
  The area of the center of pressure during upright stance did not change from Day 3 to 30 postinjury with respect to pre-injury status (P > .05). However, balance deficits induced by visual field motion were present up to 30 days postinjury. Destabilizing effect of visual field motion was observed via significant increase of the center of pressure data (P < .05) and reduced coherence value.
  
  
  CONCLUSIONS
  Our data suggest the presence of residual sensory integration dysfunction in concussed individuals at least 30 days postinjury and may indicate a lower threshold for brain reinjury.
authors.affiliation: Department of Kinesiology, Pennsylvania State University, University Park, Pennsylvania, USA. sms18@psu.edu
authors.forename: Semyon
authors.initials: S
authors.lastname: Slobounov
authors.forename: Rick
authors.initials: R
authors.lastname: Tutwiler
authors.forename: Wayne
authors.initials: W
authors.lastname: Sebastianelli
authors.forename: Elena
authors.initials: E
authors.lastname: Slobounov
mesh_terms: D000328:Adult; D001924:Brain Concussion / Q000503:physiopathology*; D016022:Case-Control Studies; D006801:Humans; D008297:Male; D009039:Motion Perception; D010865:Pilot Projects; D004856:Postural Balance; D013997:Time Factors; D015599:Trauma Severity Indices; D014584:User-Computer Interface; D014794:Visual Fields