Exploring Network-Based Individualized Transcranial Alternating Current Stimulation (NBI-tACS) for chronic post-stroke aphasia in Cantonese

Abstract

<p> In recent years, neuromodulation research is paving a new path to enhance recovery of post-stroke aphasia adjuvant to traditional behavioral-based treatment. One of the growing techniques is the Transcranial alternating current stimulation (tACS), which involves application of rhythmic electrical current to the brain via scalp electrodes to entrain intrinsic neuronal oscillation and synchronize multiple brain regions non-invasively (Elyamany et al., 2021). This study aims to develop a novel approach of individualizing tACS to facilitate language recovery of people with chronic post-stroke aphasia (PWA) based on individual’s baseline functional network obtained by Electroencephalography (EEG).</p><p> This ongoing investigation involves two phases. Phase 1 involves an exploratory analysis of the differences of EEG-derived functional networks during speech production tasks between PWA and healthy controls (HC). Graph theoretical analysis (Ismail & Karwowski, 2020) will be used to delineate the global and nodal network properties in group level and individual level, and based on that, to identify biomarkers of aphasia and individualized stimulation targets. In phase 2, a clinical experiment will be conducted to examine the immediate neuromodulatory effect of single-session individualized tACS comparing with generalized stimulation protocol and sham stimulation. Analysis will be focused on whether the stimulation is effective to modulate the biomarkers and whether individualized condition outperforms other conditions.</p><p> Preliminary results from 16 PWA and 12 HC suggested the integration and segregation properties of PWA’s network are weakened compared to HC, potential stimulation targets were identified based on specific selection principles. Completed results will be available after finishing data collection next year.</p>