In this feasibility study, lithium carbonate (target 0.4 to 0.8 mmol/L) will be given open-label for 60 days, to consenting patients with unilateral ischemic cortical lesions. Total gray matter volume using magnetic resonance imaging will also be measured at baseline and termination, and related to changes in clinical outcomes (standardized scales measuring cognitive, activities of daily living, motor recovery) performed at the time of the MRIs. We expect to find that post-stroke patients receiving lithium will have increases in gray matter volume, and that increase in gray matter volume will predict improvements in clinical outcomes over 60 days. In addition, since lithium has been shown to increase serum concentration of the neurotrophic factor, BDNF, we will explore the relationship between plasma BDNF concentrations and neurological and clinical outcomes.