The acute phase of stroke is characterized by an enhancement of neural plasticity which supports rapid motor recovery. It is unclear whether acute stroke patients can acquire new motor skills with their affected upper limb. The aims of this research program are: 1. To test the capacity of acute stroke patients (\< 21 days) to learn and retain a complex unimanual motor skill. 2. To explore whether acute stroke to different brain regions (quantified with brain MRI) induces specific deficits in motor skill learning. 3. To compare acute stroke patients with healthy individuals and with chronic stroke patients.