Many individuals are often left with problems moving their arm and hand, months to even years after a stroke. Recent progress in research suggests the application of non-invasive brain stimulation, such as transcranial direct current stimulation (TDCS), in conjunction with rehabilitation exercises can further improve a person's ability to move after stroke. However, the problem is that this doesn't work for everyone, and researchers do not know why. One reason may be that TDCS is currently applied using a one-size-fits-all approach. Researchers apply the same type of TDCS to everyone, assuming the stroke affects everyone in the same way. But, researchers know this is not the case. For example, each person will likely have different amounts of damage to brain regions that control movements. A better understanding of how the stroke uniquely affects a person's brain will help us to know which is the correct type of TDCS to apply for that person. Therefore, the objective of this research is to determine whether the amount of damage to brain regions that control movements can predict which type of TDCS will be more effective to help a person improve their ability to move. Participants will undergo 1 session of magnetic resonance imaging, and three sessions of TDCS.

Inclusion Criteria:

• unilateral first time stroke in middle cerebral artery territory
• greater 3 months post-stroke
• able to raise arm onto a table from a seated position

Exclusion Criteria:

• severe cognitive or comprehension deficits that may compromise informed consent or understanding of instructions
• severe apraxia and neglect
• neurodegenerative or psychiatric disease
• contraindications to MRI and TDCS (e.g. metal in head, pacemaker, claustrophobia)