Diffuse brain damage can occur with no signs of 'concussion' in rats, reports study

A standard experimental model of concussion in rats causes substantial brain damage --- but no behavioral changes comparable to those seen in patients with concussion, reports a study. The results highlight the "disconnect" between preclinical and clinical studies of concussion. The study also adds to concerns over the possible long-term effects of repeated, "subconcussive" brain trauma -- causing no concussion symptoms -- in humans.