Mochizuki George, Boe Shaun G, Marlin Amanda, McIlroy William E
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.
Laboratory for Brain Recovery and Function, School of Physiotherapy, Dalhousie University, Halifax, NS, Canada; Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada.
Neuroscience. 2017 Apr 21;348:143-152. doi: 10.1016/j.neuroscience.2017.02.014. Epub 2017 Feb 16.
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.
姿势不稳定的准备工作会调动皮质资源，以优化代偿性平衡反应。这些皮质资源在认知双任务活动中的参与，可能会影响适当准备和优化对不稳定反应的能力。本研究的目的是确定认知双任务活动是否会影响姿势不稳定前后的皮质活动。在10名健康参与者中，采用前倾-释放范式诱发姿势不稳定。扰动在时间上要么是可预测的（PRED），要么是不可预测的（UNPRED），并在有（COG）或没有认知双任务的情况下呈现，以试验块的形式呈现。从多个额叶电极部位记录脑电图。脑电图数据在不同条件下的25-35次试验中进行平均。在Cz部位对扰动前皮质活动的曲线下面积以及扰动后皮质活动的峰值潜伏期和幅度进行量化，并在不同条件下进行比较。同时进行的认知任务的表现降低了在可预测姿势不稳定发作之前扰动前皮质活动的平均（SE）幅度（PRED：18.7(3.0)mVms；PRED-COG：14.0(2.3)mVms）。虽然认知负荷水平在可预测条件下影响扰动后N1电位的幅度，但在不可预测条件下，认知双任务期间N1没有变化（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）。认知任务的表现延迟并降低了初始腓肠肌反应的幅度。研究结果表明，当姿势不稳定在时间上可预测时，扰动前后的皮质活动会受到认知干扰物的影响。干扰也会影响相关的肌肉反应。
