Effect of lower limb mirror visual feedback on cortical activation in healthy subjects: a self-controlled randomized trail.

Abstract

Background: Mirror visual feedback (MVF) has been widely applied in the recovery of upper limb motor dysfunction after stroke, but its application in the neurological rehabilitation of the lower limbs is relatively rare, and the neural mechanism of MVF on the lower limbs is not yet clear. This study aims to explore the impact of lower limb mirror visual feedback (LLMVF) on the cerebral cortex and its possible neural mechanisms.

Method: 23 healthy subjects were selected to conduct a self-controlled randomized study using a block design, and functional near-infrared spectroscopy (fNIRS) was used to monitor the activation of brain regions in real LLMVF and sham LLMVF. The left lower limb of the subject was set as the active leg to perform active knee flexion and extension movements, and the right lower limb was set as the observation leg (shielded behind the mirror without any movement).

Results: The mean HbO changes of LLMVF was significantly higher in the bilateral premotor and supplementary motor cortex (PM + SMA) (right: p = 0.010, left: p = 0.049), the bilateral dorsolateral prefrontal cortex (DLPF) (right: p = 0.030, left: p = 0.003), the left S1 (p = 0.011), and the right FP (p = 0.033) compared to the sham LLMVF.

Conclusion: LLMVF increases neural activity in the sensory and motor related areas, indicating that LLMVF can promote more activation of brain functional areas, which verifies the top-down positive effect of LLMVF.