Noninvasive Brain Imaging and Stimulation in Post-Stroke Motor Rehabilitation: A Review

This article provides a comprehensive review of the current state of noninvasive brain imaging and brain stimulation in motor rehabilitation after stroke. The functional organization of the brain is determined by brain network connections. Brain imaging enables us to map the network organization of the brain, so as to assess the motor function in a stroke state. The noninvasive functional imaging techniques include electroencephalography (EEG) and magnetoencephalography (MEG) with the better temporal resolution, and functional magnetic resonance imaging (fMRI) and functional near-infrared spectroscopy (fNIRS) with better spatial resolution. Based on single-mode or multimode imaging methods, the changes of brain networks caused by stroke and during motor recovery progress can be observed. Brain stimulation is an effective way to reorganize brain networks. Transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) are the most widely studied noninvasive neuromodulation techniques. Combined with imaging, brain stimulation can alter brain networks in controlled ways and making neuromodulation a closed loop. This review also outlines the methods of facilitate motor rehabilitation: 1) multimode imaging for motor assessment; 2) brain stimulation combined with rehabilitation training; 3) close-loop motor rehabilitation; and 4) influencing factors motor rehabilitation.