PROJECT SUMMARY The rationale for this proposal is that synaptic integrity is essential for neuronal function. Disruptions to synaptic integrity are downstream of common TBI pathophysiological events including neuronal cell death, axonal injury, p-tau aggregation, and neuroinflammation. The ability to detect discrete changes in synaptic integrity – regardless of the upstream mechanism of synapse loss – will allow clinicians to track the ability of clinical interventions to improve chronic outcome in patients. The objective of this proposal is to use measures of synaptic integrity to predict chronic behavioral outcomes, and to validate Hcorr as a non-invasive marker of synaptic integrity for use in TBI.