Non-invasive Brain Imaging and Stimulation in Post-stroke Motor Rehabilitation: A Review

Motor dysfunction is the common sequela of stroke, which seriously affects the patients’ daily life. Brain imaging is primarily employed to reconstruct the brain’s structural and functional networks to assess motor function during motor rehabilitation. Non-invasive brain imaging techniques have been widely used due to the non-surgical advantages. Electroencephalography (EEG) and magnetoencephalography (MEG) are measurements of electromagnetic feld changes during brain activity. At the same time, functional magnetic resonance imaging (fMRI) and functional near-infrared spectroscopy (fNIRS) are measurements of hemodynamic state during brain activity. Brain network consisting of functional connectivity and effective connectivity could be established based on brain imaging. Multimodal imaging can overcome the limitation of single-mode, making the motor function assessment more comprehensive and accurate. Mathematical models are required for studying connectivity and relationships among brain areas. Brain activity can be modulated through brain stimulation to enhance motor rehabilitation based on motor function assessments. Although not yet included in clinical guidelines, transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) have been shown in numerous clinical trials to promote bilateral brain balance. Brain network reorganization guides therapeutic strategies integrating brain stimulations. Although brain imaging and brain stimulation on stroke motor rehabilitation are well-studied forms, a thorough between imagingbased motor assessment and stimulation-based rehabilitation strategy is still lacking. This narrative review aims to summarize the methods of motor function assessment using brain imaging and interventions for motor function rehabilitation using brain stimulation after stroke, which would be helpful to establish a closed-loop rehabilitation approach.