The study includes three groups of infants: (i) group A consisting of preterm infants (gestational age of <36 weeks), (ii) group B consisting of term infants admitted to the Newborn Intensive Care Unit (NICU) at Boston Children's Hospital (BCH) for therapeutic hypothermia who are at risk of developing hypoxic ischemic injury (HIE) or admitted with concern for neonatal stroke, and (iii) group C consisting of healthy term infants in the community and term infants admitted to the NICU who had an initial uncomplicated postnatal course that will serve as the control group. In group A, infants will be further classified as not having a brain lesion in their anatomical MRI scan (group A1) or having a brain lesion in their MRI (group A2).