title: Performance of a concurrent cognitive task modifies pre- and post-perturbation-evoked cortical activity.
abstract: Preparation for postural instability engages cortical resources that serve to optimize compensatory balance responses. Engagement of these cortical resources in cognitive dual-task activities may impact the ability to appropriately prepare and optimize responses to instability. The purpose of this study was to determine whether cognitive dual-task activities influenced cortical activity preceding and following postural instability. Postural instability was induced using a lean-and-release paradigm in 10 healthy participants. Perturbations were either temporally predictable (PRED) or unpredictable (UNPRED) and presented with (COG) or without a cognitive dual-task, presented in blocks of trials. The electroencephalogram was recorded from multiple frontal electrode sites. EEG data were averaged over 25-35 trials across conditions. Area under the curve of pre-perturbation cortical activity and peak latency and amplitude of post-perturbation cortical activity were quantified at the Cz site and compared across conditions. Performance of the concurrent cognitive task reduced the mean (SE) magnitude of pre-perturbation cortical activity in advance of predictable bouts of postural instability (PRED: 18.7(3.0)mVms; PRED-COG; 14.0(2.3)mVms). While the level of cognitive load influenced the amplitude of the post-perturbation N1 potential in the predictable conditions, there were no changes in N1 with a cognitive dual task during unpredictable conditions (PRED: -32.1(3.2)µV; PRED-COG: -50.8(8.4)µV; UNPRED: -65.0(12.2)µV; UNPRED-COG: -64.2(12.7)µV). Performance of the cognitive task delayed and reduced the magnitude of the initial gastrocnemius response. The findings indicate that pre- and post-perturbation cortical activity is affected by a cognitive distractor when postural instability is temporally predictable. Distraction also influences associated muscle responses.
authors.affiliation: Heart and Stroke Foundation Canadian Partnership for Stroke Recovery, Sunnybrook Research Institute, Toronto, ON, Canada; Department of Physical Therapy, University of Toronto, Toronto, ON, Canada; Hurvitz Brain Sciences Research Program, Sunnybrook Research Institute, Toronto, ON, Canada; Mobility Research Team, Toronto Rehabilitation Institute, Toronto, ON, Canada. Electronic address: george.mochizuki@sunnybrook.ca.
authors.forename: George
authors.initials: G
authors.lastname: Mochizuki
authors.affiliation: Laboratory for Brain Recovery and Function, School of Physiotherapy, Dalhousie University, Halifax, NS, Canada; Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada.
authors.forename: Shaun G
authors.initials: SG
authors.lastname: Boe
authors.affiliation: Mobility Research Team, Toronto Rehabilitation Institute, Toronto, ON, Canada.
authors.forename: Amanda
authors.initials: A
authors.lastname: Marlin
authors.affiliation: Heart and Stroke Foundation Canadian Partnership for Stroke Recovery, Sunnybrook Research Institute, Toronto, ON, Canada; Hurvitz Brain Sciences Research Program, Sunnybrook Research Institute, Toronto, ON, Canada; Mobility Research Team, Toronto Rehabilitation Institute, Toronto, ON, Canada; Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada.
authors.forename: William E
authors.initials: WE
authors.lastname: McIlroy
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology; D002540:Cerebral Cortex / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D004856:Postural Balance / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D055815:Young Adult
keywords: EEG; balance; dual-task; preparation