PROJECT SUMMARY/ABSTRACT Sports-related concussion, a type of mild traumatic brain injury (TBI), is a significant public health concern, especially given recent discoveries that athletes with a history of concussion are more likely to sustain new injuries when they return to high-risk activity, which is linked to adverse long-term health outcomes. Importantly, this heightened risk of new injury has been found in young athletes who were ?cleared? to return to play using current clinical evaluation protocols, suggesting that these protocols are suboptimal. An option for improved evaluation is dual task assessment ? appraisal of motor performance with a secondary task added, typically a cognitive distractor task. Notably, dual task assessments have elicited diminished motor abilities in young athletes who were ?cleared? to return to play after concussion. These diminished motor abilities may underlie the increased likelihood for new injury, however, it is currently unclear why clinical evaluation protocols fail to detect them. Therefore, as a logical first step, the objective of the current proposal is to better understand why diminished motor abilities are missed with clinical evaluation protocols. Preliminary neuroimaging data and dual task performance data suggest that ?cleared? youth with a history of concussion compensate for diminished motor ability by recruiting additional neural attention resources to support single task performance, or motor performance without a cognitive distractor task. Conceivably, this compensatory recruitment is insufficient for dual task performance, which is why dual task assessments elicit diminished motor abilities. Current clinical evaluation protocols include subjective symptom reporting and behavioral assessments administered in a single task design (i.e. without secondary task distraction). However, nearly all sports require motor performance in the presence of distraction. This proposal includes behavioral measures with improved ecological validity (i.e. dual task assessments) and seeks to elucidate neural underpinnings of diminished motor abilities in ?cleared? young athletes with recent concussion. Neuroimaging methods include a well- established electroencephalography (EEG) paradigm and an innovative technique ? a functional near-infrared spectroscopy (fNIRS) system that can accommodate gross motor movement. ?Cleared? young athletes with recent concussion will be compared to never-concussed young athletes and evaluated on single and dual task performance with simultaneous neural recording. It is anticipated that these ?cleared? young athletes will show comparable single task performance but ? importantly ? have poorer dual task performance and demonstrate aberrant recruitment of neural attention regions compared to never-concussed peers. These findings would suggest that some ?cleared? athletes have not completely recovered from their concussion. By identifying neural characteristics associated with diminished motor abilities and increased risk for new injury, this work will have a significant impact by: 1) better describing the neurophysiology of concussion and 2) laying the foundation for future studies designed to identify and reduce short- and long-term risk of concussion.