Neurovascular Changes Characterize Split-belt Adaptation in Chronic Stroke Survivors: Preliminary Results

Previous studies implicate localized cortical regions in locomotor function recovery in stroke survivors, however, little is known about the mechanisms which underlie locomotor adaptation recovery. Locomotor adaptation in stroke survivors is mired due to weak bilateral coordination during gait. In this ongoing study, bilateral incoordination in gait is targeted with a split-belt paradigm while cortical neurovascular changes during the adaptation are recorded with Functional Near Infrared Spectroscopy (fNIRS). Chronic stroke survivors walked on a split-belt treadmill while wearing an fNIRS device. Participants walked in baseline, splitbelt, and catch conditions. A continuous wave fNIRS system utilized two different wavelengths (~695 and ~830 nm) sampling at 10 Hz measured cortical activity. Task-related cortical activity was computed based on the amount of oxygenated (OxyHb) hemoglobin during the locomotor adaptation task. Our paradigm yielded 24 channels on each side of the head. Baseline levels of OxyHb were calculated for 30 seconds prior to starting each trial with the subjects standing quietly. The difference from baseline was calculated during the first and last 30 seconds of each trial to determine initial and adaptation changes. Preliminary results from the study demonstrate the following for the primary motor and associated cortices: 1) higher levels of OxyHb on the non-affected side, 2) Increased OxyHb during initial adaptation, 3) early to late splitbelt adaptation was characterized by a reduction in OxyHb and 4) Increase in OxyHb during catch trial. Characteristic neurovascular changes are demonstrated in stroke survivors during locomotor adaptation which enhances our mechanistic understanding of adaptive changes post-stroke