MOVEMENT-INFORMED CLOSED-LOOP BETA FREQUENCY TACS IN CHRONIC STROKE SURVIVORS

Stroke is one of the leading causes of acquired disability across the globe. While most stroke survivors display the highest recovery rates during early phases after stroke, continued neurorehabilitation after these ‘natural’ recovery windows remains essential to reduce personal as well as societal costs. Previous research focussing on the beta frequency band has shown attenuated movement-related beta resynchronisation in the motor cortex in stroke survivors, correlating with functional outcomes. Additionally, beta frequency transcranial alternating current stimulation (tACS) increased beta post-movement resynchronisation and improved motor performance in healthy controls. Here, we assess whether movement-informed closed-loop beta frequency tACS could improve motor rehabilitation in chronic stroke survivors with upper limb motor impairment. Baseline motor function was assessed through clinical and objective measures, as well as self-reported impairment scores for all participants. Stroke survivors participated in two experimental sessions, during which they performed reaching-grasping movements with real or sham stimulation during kinematic and EEG recordings. Nearly all participants displayed moderately to severely impaired upper limb movement and had motor-related cortical and/or subcortical stroke involvement. Furthermore, preliminary analysis shows a trend towards within-subject changes in movement speed in stimulation versus sham sessions. We are currently performing detailed analysis of kinematic metrics such as target accuracy, trajectory variability, and smoothness. In addition, we will investigate whether beta-frequency tACS leads to similar EEG changes as in healthy controls. Together, these data provide a promising starting point for non-invasive transcranial alternating stimulation in chronic stroke survivors as an adjunct for neurorehabilitation.