Inhibition of neocortical plasticity during development by a moderate concussive brain injury

To determine if a moderate traumatic brain injury (TBI) sustained early in life alters the capacity for developmental plasticity, 17-20-day-old rat pu ps received a lateral fluid percussion and then reared in an enriched envir onment for 17 days. Compared to sham-injured controls, this moderate TBI pr evented the increase in cortical thickness (1.48 vs. 1.68 mm, p < 0.01) as well as the corresponding enhancement in cognitive performance in the Morri s Water Maze (39 vs. 25 trials to criterion, p < 0.05), These injured anima ls exhibited no significant neuronal degeneration and no evidence of neurol ogic or motor deficits, These findings strongly support the conclusion that a diffuse brain injury is capable of inhibiting both anatomical and cognit ive manifestations of experience-dependent developmental plasticity.