title: Interactions between cognitive and sensory load while planning and controlling complex gait adaptations in Parkinson's disease.
abstract: BACKGROUND
  Recent research has argued that removal of relevant sensory information during the planning and control of simple, self-paced walking can result in increased demand on central processing resources in Parkinson's disease (PD). However, little is known about more complex gait tasks that require planning of gait adaptations to cross over an obstacle in PD.
  
  
  METHODS
  In order to understand the interaction between availability of visual information relevant for self-motion and cognitive load, the current study evaluated PD participants and healthy controls while walking toward and stepping over an obstacle in three visual feedback conditions: (i) no visual restrictions; (ii) vision of the obstacle and their lower limbs while in complete darkness; (iii) vision of the obstacle only while in complete darkness; as well as two conditions including a cognitive load (with a dual task versus without a dual task). Each walk trial was divided into an early and late phase to examine changes associated with planning of step adjustments when approaching the obstacle.
  
  
  RESULTS
  Interactions between visual feedback and dual task conditions during the obstacle approach were not significant. Patients with PD had greater deceleration and step time variability in the late phase of the obstacle approach phase while walking in both dark conditions compared to control participants. Additionally, participants with PD had a greater number of obstacle contacts when vision of their lower limbs was not available specifically during the dual task condition. Dual task performance was worse in PD compared to healthy control participants, but notably only while walking in the dark regardless of visual feedback.
  
  
  CONCLUSIONS
  These results suggest that reducing visual feedback while approaching an obstacle shifts processing to somatosensory feedback to guide movement which imposes a greater demand on planning resources. These results are key to fully understanding why trips and falls occur in those with PD.
authors.affiliation: Sun Life Financial Movement Disorders Research & Rehabilitation Centre, Wilfrid Laurier University, Waterloo, ON, N2L 3C5, Canada. fpieruccinifaria@wlu.ca.|Psychology Department, Wilfrid Laurier University, Waterloo, ON, N2L 3C5, Canada. fpieruccinifaria@wlu.ca.
authors.forename: Frederico
authors.initials: F
authors.lastname: Pieruccini-Faria
authors.affiliation: Sun Life Financial Movement Disorders Research & Rehabilitation Centre, Wilfrid Laurier University, Waterloo, ON, N2L 3C5, Canada. kaehgoet@uwaterloo.ca.
authors.forename: Kaylena A
authors.initials: KA
authors.lastname: Ehgoetz Martens
authors.affiliation: Sun Life Financial Movement Disorders Research & Rehabilitation Centre, Wilfrid Laurier University, Waterloo, ON, N2L 3C5, Canada. c2silvei@uwaterloo.ca.
authors.forename: Carolina Ra
authors.initials: CR
authors.lastname: Silveira
authors.affiliation: Sun Life Financial Movement Disorders Research & Rehabilitation Centre, Wilfrid Laurier University, Waterloo, ON, N2L 3C5, Canada. jjones@wlu.ca.|Psychology Department, Wilfrid Laurier University, Waterloo, ON, N2L 3C5, Canada. jjones@wlu.ca.|Laurier Centre for Cognitive Neuroscience, Wilfrid Laurier University, Waterloo, ON, N2L 3C5, Canada. jjones@wlu.ca.
authors.forename: Jeffery A
authors.initials: JA
authors.lastname: Jones
authors.affiliation: Sun Life Financial Movement Disorders Research & Rehabilitation Centre, Wilfrid Laurier University, Waterloo, ON, N2L 3C5, Canada. qalmeida@wlu.ca.
authors.forename: Quincy J
authors.initials: QJ
authors.lastname: Almeida
mesh_terms: D000222:Adaptation, Physiological; D000368:Aged; D016022:Case-Control Studies; D003071:Cognition; D056228:Feedback, Sensory; D005260:Female; D005684:Gait; D020233:Gait Disorders, Neurologic / Q000209:etiology / Q000503:physiopathology* / Q000523:psychology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications / Q000503:physiopathology* / Q000523:psychology; D011597:Psychomotor Performance; D013647:Task Performance and Analysis; D014796:Visual Perception; D016138:Walking