Effect of traumatic brain injury on mouse spatial and nonspatial learning in the Barnes circular maze.

Controlled cortical impact (CCI) is a relatively new model of traumatic brain injury in the mouse, which, in combination with behavioral and histological methods, has potential for elucidating underlying mechanisms of neurodegeneration using genetically altered animals. Previously, we have demonstrated impaired spatial learning in a water maze task following CCI injury at a moderate level. There are many difficulties associated with this task, however, such as stress, physical demand, and the multiple trials over days required for satisfactory training. As a potential alternative to the water maze, we adapted the Barnes circular maze to our mouse model and assessed spatial/nonspatial learning following injury. Mice were trained to locate a dark tunnel, hidden beneath one of 40 holes positioned around the perimeter of a large, flat, plastic disk, brightly illuminated by four overhead halogen lamps. Sham-operated animals rapidly acquired this task, exhibiting reduced latency to find the tunnel and a more efficient search strategy as compared with injured mice. This difference was not due to visuomotor deficits, as all mice performed equally well in a cued version of the same task. These results demonstrate spatial learning impairment following CCI injury in a task that offers an efficient alternative to the water maze.