Modulation of Brain Rhythms in Stroke

The goal of this research study is to examine communication between brain and muscle in individuals with stroke and determine if applying non-invasive brain stimulation to different parts of the brain improves this communication and performance on a hand squeezing task. The investigators will fit participants with an electroencephalography (EEG) cap and place electromyography (EMG) stickers on participants hand and arm muscles to record brain and muscle activity, respectively. Participants will complete a single research visit lasting approximately 3 hours. During this visit, participants will receive two different types of non-invasive brain stimulation: \[1\] stimulation to the motor part of the brain and \[2\] stimulation to the visual part of the brain. Participants will be randomized so that half will receive stimulation to the motor part of the brain first followed by stimulation to the visual part of the brain second and vice versa. Participants will complete three blocks of hand squeezing trials using the stroke-affected (weak) hand. During the first block of squeezing trials, no brain stimulation will occur. During the second and third blocks, participants will receive stimulation just before each hand squeezing trial. The investigators will record participants' brain and muscle activity during these blocks of hand squeezing trials. Additionally, participants will also complete screening tests and exams looking at mood, motor function, and cognition.