Approximately 30,000 babies annually are born with extremely low birth weight (ELBW) in the US. These babies often have motor and/or visual problems when they grow up. It is very important to identify high risk ELBW infants as early as possible, so that the investigators can treat them earlier to prevent poor development. Neurological examination at early age is not good enough to identify high risk ELBW infants. One the other hand, some magnetic resonance imaging (MRI) methods such as diffusion tensor imaging (DTI) and resting state functional MRI (rfMRI) have shown great sensitivity to brain injury which may cause motor and visual problems. Therefore, the investigators propose to use DTI and rfMRI on ELBW infants at a very early age to predict long−term outcome and to identify infants who are at high risk of having motor and/or visual problems when they grow up.