MORRIS WATER MAZE DEFICITS IN RATS FOLLOWING TRAUMATIC BRAIN INJURY -LATERAL CONTROLLED CORTICAL IMPACT

This experiment utilized a laterally placed controlled cortical impact model of traumatic brain injury (TBI) to assess changes on spatial le arning and memory in the Morris water maze (MWM), Adult rats were subj ected to one of two different levels of cortical injury, mild (1 mm) o r moderate (2 mm) deformation, and subsequently tested for their abili ty to learn (acquisition) or remember (retention) a spatial task, 7 or 14 days after injury, Results revealed an injury-dependent deficit fo r experimental animals compared to sham-operated controls. Not only di d the TBI result in longer escape latencies, but also significant defi cits in search time and relative target visits, Although the moderatel y injured animals demonstrated significant histopathology in the corte x and hippocampus, mildly injured subjects demonstrated no obvious tis sue destruction, but did manifest significant behavioral change. These results demonstrate that a laterally placed controlled cortical impac t is capable of producing significant cognitive deficits on both acqui sition and retention paradigms utilizing the MWM.