Changes in cerebral blood flow before, during, and after forward and backward walking in stroke patients trained using virtual reality walking videos with deliberately induced inaccuracies in walking speed estimations.

[Purpose] The aim of this study was to examine the effects of virtual reality (VR) training, with deliberately induced inaccuracies in walking speed estimations, on brain activity. [Participants and Methods] The study participants were 21 stroke patients, and the walking tasks involved forward and backward walking. While the VR walking speed was set at 3 km/h, estimation errors were induced by using an actual walking speed of 1 km/h during the walking tasks. Cerebral blood flow was measured using two functional near-infrared spectroscopy (fNIRS) channels located over the left and right prefrontal cortices, to determine changes in oxyhemoglobin levels from the resting state. Cerebral hemodynamics were compared during and after the VR training. [Results] The backward walking task induced a significant increase in cerebral blood flow in the right prefrontal cortex during and after the VR training. No significant changes were observed during the forward walking task. [Conclusion] In the backward walking condition, greater activation of the right prefrontal cortex was observed during and immediately after the VR training. Watching VR may have led to inaccurate walking-speed estimations, necessitating postural control (which may be attributed to the activation of the prefrontal cortex) during walking.