Frontal, Sensorimotor, and Posterior Parietal Regions Are Involved in Dual-Task Walking After Stroke

Abstract

Background: Walking within the community requires the ability to walk while simultaneously completing other tasks. After a stroke, completing an additional task while walking is significantly impaired, and it is unclear how the functional activity of the brain may impact this.

Methods: Twenty individual in the chronic stage post-stroke participated in this study. Functional near-infrared spectroscopy (fNIRS) was used to measure prefrontal, pre-motor, sensorimotor, and posterior parietal cortices during walking and walking while completing secondary verbal tasks of varying difficulty. Changes in brain activity during these tasks were measured and relationships were accessed between brain activation changes and cognitive or motor abilities.

Results: Significantly larger activations were found for prefrontal, pre-motor, and posterior parietal cortices during dual-task walking. Increasing dual-task walking challenge did not result in an increase in brain activation in these regions. Higher general cognition related to lower increases in activation during the easier dual-task. With the harder dual-task, a trend was also found for higher activation and less motor impairment.

Conclusions: This is the first study to show that executive function, motor preparation/planning, and sensorimotor integration areas are all important for dual-task walking post-stroke. A lack of further brain activation increase with increasing challenge suggests a point at which a trade-off between brain activation and performance occurs. Further research is needed to determine if training would result in further increases in brain activity or improved performance.

Keywords: dual-task; functional near-infrared spectroscopy; gait; posterior parietal cortex (PPC); pre-motor cortex (PMC); prefrontal cortex (PFC); sensorimotor cortex (SMC); stroke.

Figure 1

Schematic of task procedure. (A) Indicates the procedure for each trial. (B) Indicates the order of the conditions. Each participant started with 4–5 trials of ST-Walk first then they were randomized to either DT-Easy or DT-Hard walking conditions next.

Figure 2

Montage of optode placement over the scalp.

Figure 3

Average and standard error activation during each walking condition. #Indicates a significant difference between conditions with p <0.05 ^*indicates a significant difference between conditions with p <0.0125. PFC, prefrontal cortex; PMC, pre-motor cortex; SMC, sensorimotor cortex; PPC, posterior parietal cortex.

Figure 4

Change in brain activation from (y-axis) ST-Walk to DT-Easy plotted against Montreal Cognitive Assessment (MoCA) scores (x-axis). ^*indicates significant correlation after Benjamini–Hochberg correction. PFC, prefrontal cortex; PMC, pre-motor cortex; SMC, sensorimotor cortex; PPC, posterior parietal cortex.

Figure 5

Change in brain activation from (y-axis) ST-Walk to DT-Hard plotted against the Fugl-Meyer Lower Extremity (FMLE) scores (x-axis). #Indicates significant correlation with alpha at 0.05. PFC, prefrontal cortex; PMC, pre-motor cortex; SMC, sensorimotor cortex; PPC, posterior parietal cortex.