title: Gaze behavior of older adults during rapid balance-recovery reactions.
abstract: BACKGROUND
  Rapid stepping reactions are a prevalent response to sudden loss of balance and play a crucial role in preventing falls. A previous study indicated that young adults are able to guide these stepping reactions amid challenging environmental constraints using "stored" visuospatial information. This study addressed whether healthy older adults also use "stored" visuospatial information in this manner, or are more dependent on "online" visual control.
  
  
  METHODS
  Gaze behavior was recorded during rapid forward-stepping reactions evoked by unpredictable platform perturbation, as participants performed a concurrent task demanding visual attention. Challenging obstacles and/or step targets were used to increase demands for accurate foot motion. Twelve healthy older adults (61-73 years) were compared to 12 young adults (22-29 years) tested in a previous study.
  
  
  RESULTS
  Similar to young adults, older participants seldom redirected gaze downward in response to the perturbation (11% of trials), yet were commonly able to clear the obstacle (74% of trials) or land on the target (41% of trials) while stepping to recover balance. The threat posed by the obstacle apparently prompted older adults to initiate early downward saccades during a small proportion (18%) of obstacle trials; however, this did not improve ability to clear the obstacle.
  
  
  CONCLUSIONS
  Aging did not alter the predominant visual-control strategy used to guide the stepping reactions. Both young and older persons typically used stored visuospatial information, thereby allowing vision/attention to be switched to other demands during the stepping reaction and minimizing head/eye movements that could exacerbate the destabilizing effect of the balance perturbation.
authors.affiliation: Centre for Studies in Aging, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, Ontario, Canada.
authors.forename: John L
authors.initials: JL
authors.lastname: Zettel
authors.forename: William E
authors.initials: WE
authors.lastname: McIlroy
authors.forename: Brian E
authors.initials: BE
authors.lastname: Maki
mesh_terms: D000058:Accidental Falls / Q000517:prevention & control; D000328:Adult; D000368:Aged; D005133:Eye Movements; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D004856:Postural Balance / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D012438:Saccades; D013028:Space Perception