Healthy volunteers and patients with cerebral palsy between 6 and 18 years of age may be eligible for this study. All candidates will be screened with a medical history, physical examination, and psychological testing. In addition, patients with cerebral palsy will have hearing and vision tests, a review of their medical records, and a magnetic resonance imaging (MRI) scan if one has not been done within the past year. For this test, the patient lies on a table that slides into a narrow metal cylinder with a strong magnetic field (the scanner). The scanning time usually lasts between 45 and 90 minutes.