Cerebral Palsy and the Study of Brain Activity During Motor Tasks

* INCLUSION CRITERIA * Age 5 years and older * Surgery free for six months in either the upper or lower extremities. * Free from botulinum toxin injections within four months in either the upper or lower extremities. * Either a healthy volunteer or have a diagnosis of a childhood-onset (before 13 years of age) brain injury resulting in motor impairment of one arm and one leg on the same side of the body or motor impairment of both legs or have a diagnosis of childhood-onset (before 13 years of age) peripheral injury resulting in sensory or motor impairment of any limb or multiple limbs. * Able to understand and follow simple directions that include how to perform a repetitive task and when to start and stop doing the task, based on parent report if the subject is a child and physician observation during history and physical examination. * Able to walk at least 20 feet without stopping with or without a walking aid * Able to provide informed consent (Guardian or parent of child participants) or verbal/written assent as appropriate (for child participant). * Agreement to not drink caffeine or alcohol for 24 hours before each assessment session because both agents can modify brain activity and may confound outcome measures. This restriction does not apply to the training sessions in Objective 3. EXCLUSION CRITERIA: * Any neurological, musculoskeletal or cardiorespiratory injury, health condition, or diagnosis other than childhood-onset brain or peripheral injury that would affect the ability to mentally concentrate or move a body part repetitively for short periods of time. Examples of this include, but are not limited to, congestive heart failure, end stage cardiac disease, or fractures that have not completely healed. * Uncontrolled seizures. * Concurrent use of medicines for muscle tone (e.g., baclofen, trihexyphenedyl, dantrolene sodium, tizanidine, or carbidopa/levodopa). If patients are taking these medications daily, the treating physician will be contacted by the MAI to determine if it is acceptable for the subject to temporarily discontinue the medication(s) for 24 hours prior to participating in testing for this study for each of the first 2 objectives. If that is not deemed to be safe, the subject will be excluded. Subjects who are on these medications will not be allowed to participate in Objective 3. * Pregnancy: Childbearing potential will be determined during the history and physical exam and urine pregnancy test may be required * Adult who can t consent for themselves. To participate in Objective 1, it is preferable that all subjects be willing and able to have, or have previously had, a structural MRI to aid in the interpretation of results. Inability or refusal to complete an MRI, or to provide access to a previous structural MRI scan, will not constitute an exclusion criterion for this study. Additional exclusion criteria for MRI * Inability to lie flat on the back for up to 45 minutes without sedation. * Discomfort being in small spaces for up to 45 minutes. * Cardiac pacemakers, implanted medication pumps, intracardiac lines, or acute, unstable cardiac disease, with intracranial implants (e.g. aneurysm clips, shunts, stimulators, cochlear implants, or electrodes) or any other metal object within or near the head, excluding the mouth that cannot be safely removed. Additional exclusion criteria for EEG -History of allergic reaction to water-based electrode gel