Premotor and Posterior Parietal Cortex Activity is Increased for Slow, as well as Fast Walking Poststroke: An fNIRS Study

Abstract

Methods: Twenty individuals in the chronic stage of stroke walked: (1) at their normal pace, (2) slower than normal, and (3) as fast as possible. Functional near-infrared spectroscopy was used to assess bilateral prefrontal, premotor, sensorimotor, and posterior parietal cortices during walking.

Results: No significant differences in laterality were observed between walking speeds. The ipsilesional prefrontal cortex was overall more active than the contralesional prefrontal cortex. Premotor and posterior parietal cortex activity were larger during slow and fast walking compared to normal-paced walking with no differences between slow and fast walking. Greater increases in brain activation in the ipsilesional prefrontal cortex during fast compared to normal-paced walking related to greater gait speed modulation.

Conclusions: Brain activation is not linearly related to gait speed. Ipsilesional prefrontal cortex, bilateral premotor, and bilateral posterior parietal cortices are important areas for gait speed modulation and could be an area of interest for neurostimulation.

Figure 1

Average (N = 20) activation for oxyhemoglobin (HbO) and deoxyhemoglobin (HbR) during each walking condition. PFC = prefrontal cortex; PMC = premotor cortex; SMC = sensorimotor cortex; PPC = posterior parietal cortex.

Figure 2

Average and standard error (N = 20) change in laterality index for HbO during each walking condition. Positive values indicate more activation along the ipsilesional hemisphere and negative values indicate more activation along the contralesional hemisphere. PFC = prefrontal cortex; PMC = premotor cortex; SMC = sensorimotor cortex; PPC = posterior parietal cortex.