Traumatic brain injury (TBI) is a major public health problem in the United States. The application of magnetoencephalography (MEG) to the study of behavioral outcome of pediatric TBI is innovative because MEG may discern potential mechanisms for these outcomes. This potential derives from the fact that MEG is a functional neuroimaging tool that detects evidence of brain damage that eludes detection by MRI in the vast majority of cases of mild TBI and likely identifies additional lesions even in moderate to severe TBI. The goal of the proposed project is to study injury and psychosocial risk factors for the development of behavioral complications in children with TBI. The proposed study will involve a 3-month, 2-assessment, prospective longitudinal study of consecutively treated injured children with TBI (n=220) and a control group of children with orthopedic injuries (OI) not involving the brain (n=110). Assessments will include MEG and structural and functional MRI. Validated assessments of behavioral, psychiatric, neurobehavioral, and psychosocial variables will be administered. The study will examine 4 major hypotheses: (1) Abnormal slow-wave MEG activity and its reduction (healing) from 2 weeks to 3 months postinjury will occur in higher magnitude and in more brain areas in TBI versus OI children, and with greater severity of TBI. The younger the age of children with TBI the slower the recovery will be over time. (2) MEG will be more sensitive and specific than MRI in detecting damaged areas of brain and altered connectivity in children with TBI and OI. (3) Injury variables (age, MEG slow waves, FA, severity, MRI volumetric indices, presence of brain lesion) will mediate changes in postconcussion symptoms, occurrence of new-onset psychiatric disorders, and attention function changes and outcome in children with TBI and OI, independent of effects of preinjury child variables (adaptive, academic and cognitive function, and comorbid psychiatric disorders), postinjury child variables (adaptive function, coping), preinjury family variables (family function, socioeconomic status, life-events, family psychiatric history), and postinjury family variables (functioning). (4) Compared with OI, children with TBI will perform more poorly and improve less on an n-back working memory task, and demonstrate a different pattern of MEG signal activation suggestive of frontal- parietal dysfunction. This study will foster more accurate prediction, earlier identification and improved treatment of psychiatric and neurobehavioral complications related to pediatric TBI.