BDNF and Stroke: Abbreviations: AAT = Aachen Aphasia Test, BDNF = brain-derived neurotrophic factor, IFG = inferior frontal gyrus, M1 = primary motor cortex, MRI = magnetic resonance imaging, NIBS = non-invasive brain stimulation, PET = positron emission tomography, rTMS = repetitive transcranial magnetic stimulation, SLT = speech and language therapy, STG = superior temporal gyrus, tDCS = transcranial direct current stimulation, NIHSS = National Institutes of Health Stroke Scale