Abbreviated Environmental Enrichment Enhances Neurobehavioral Recovery Comparably to Continuous Exposure After Traumatic Brain Injury

Abstract

Background. Environmental enrichment (EE) is a complex living milieu that has been shown to enhance functional recovery versus standard (STD) housing after experimental traumatic brain injury (TBI) and therefore may be considered a rodent correlate of rehabilitation. However, the typical EE paradigm consists of continuous exposure to enrichment after TBI, which is inconsistent with the limited time frame in clinical rehabilitation. Objective. To determine whether abbreviated EE (ie, rehabilitation-relevant dose response) confers benefits similar to typical EE after TBI. Methods. Adult male rats received either a controlled cortical impact (2.8 mm depth at 4 m/s) or sham injury and were then randomly assigned to TBI + EE, TBI + EE (2 hours), TBI + EE (4 hours), TBI + EE (6 hours), TBI + STD, and respective sham controls. Motor (beam balance/beam walk) and cognitive (Morris water maze) performance was assessed on postoperative days 1 to 5 and 14 to 19, respectively. Results. The TBI + EE (2 hours) and TBI + EE (4 hours) groups were not statistically different from the TBI + STD group in any behavioral assessment. In contrast, the TBI + EE (6 hours) group exhibited significant enhancement of motor and cognitive performance when compared with the TBI + STD group, as well as the TBI + EE (2 hours) and TBI + EE (4 hours) groups (P < .003), and did not differ from the TBI + EE (typical) group. Conclusions. These data demonstrate that abbreviated EE (6 hours) produces motor and cognitive benefits similar to continuous EE after TBI and thus may be considered a dose-relevant rehabilitation paradigm.