EXPOSURE TO ENVIRONMENTAL COMPLEXITY PROMOTES RECOVERY OF COGNITIVE FUNCTION AFTER TRAUMATIC BRAIN INJURY

This study was designed to determine whether exposure to a complex env ironment after traumatic brain injury (TBI) would promote the recovery of cognitive function. Rats were injured at a moderate level of fluid percussion injury (2.1 atm) or were prepared for injury but were not injured (sham injury), Immediately after the injury or sham injury, th e injured/complex (n = 8) and the sham/complex (n = 7) groups were pla ced into a complex environment. The complex environment was a 89 x 89- cm enclosure with different types of bedding and objects that provided motor, ol-factory, tactile, and visual stimulation. The injured/stand ard (n = 8) and the sham/standard (n = 8) groups were returned to the animal vivarium where they were housed individually in standard wire m esh cages (24 x 20 x 18 cm). On days 11-15 (postinjury), performance i n the Morris water maze was assessed. Analysis of the latency to reach the goal platform indicated that injured animals recuperating in the complex environment performed significantly better than injured animal s recovering in the standard environment (p < 0.01). In fact, injured animals in the complex environment performed as well as both sham-inju red groups. The improved performance of injured rats recovering in the enriched environment occurred in the absence of environmentally induc ed alterations in brain weight. These results indicate that exposure t o environmental complexity enhances recovery of cognitive function aft er TBI.