Analysis Of Pre-frontal Cortex Hemodynamic Responses During Locomotive Adaptation To Compliant Surface In Individuals Post-stroke

People post-stroke often experience difficulty in walking, which is compounded when navigating uneven surfaces. Limited research has expolored the brain’s responses to walking on irregular surfaces in individuals post-stroke. PURPOSE: The purpose of this study was to analyize pre-frontal cortex (PFC) hemodynamic responses during locomotive adaptation to inregular compliant surfaces in individuals post-stroke. METHOD: Nine individuals post-stroke (mean age 70 ± 9 yrs) and 10 age-matched control participants (64.2 ± 6 yrs) completed two walking trials; 20-second straightline walking on non-compliant even (firm) and compliant irregular (soft) surfaces in random order. PFC hemodynamic activity was measured by a non-invasive neuroimaging device, functional near-infrared spectroscopy (fNIRS) and specific PFC regions of interest were compared between the two conditions, including dorsolateral prefrontal cortex (DLPFC) and frontopolar area (FPA). RESULTS: The stroke group selected significantly slower speeds for their comfortable pace walking on the soft surface, as compared to the firm surface (0.48 ± 0.14 m/s vs. 0.62 ± 0.16 m/s, p < 0.0009), and so did the control group (0.54 ± 0.05 m/s vs. 0.72 ± 0.05 m/s, p < 0.00004). Repeated measures ANOVA showed no significant difference in oxy-hemoglobin saturation (ΔHbO2) between walking conditions for either group in the PFC regions of interest. However, a trend was observed in the stroke group ΔHbO2 increased in DLPFC by 66.61% on an affected side and 99.08% on a less affected side, as well as 61.15% on the FPA when walking on the soft surface as compared to the firm surface. No significant group x condition interaction was found for ΔHbO2 across regions. A trend was noted that the stroke group increased PFC activity on the soft surface as compared to the firm condition whereas the control group exhibited a decrease of ΔHbO2 in all PFC regions. CONCLUSION: Our findings provide a scientific understanding of how challenging walking surfaces affect neural mechanisms for locomotive adaptations in individuals post-stroke. These differences should be considered when developing locomotive training for this population.