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 bra in injury in the mouse, which, in combination with behavioral and histologi cal methods, has potential for elucidating underlying mechanisms of neurode generation using genetically altered animals. Previously, we have demonstra ted impaired spatial learning in a water maze task following CCI injury at a moderate level. There are many difficulties associated with this task, ho wever, such as stress, physical demand, and the multiple trials over days r equired for satisfactory training. As a potential alternative to the water maze, we adapted the Barnes circular maze to our mouse model and assessed s patial/non-spatial learning following injury. Mice were trained to locate a dark tunnel, hidden beneath one of 40 holes positioned around the perimete r of a large, flat, plastic disk, brightly illuminated by four overhead hal ogen lamps. Sham-operated animals rapidly acquired this task, exhibiting re duced latency to find the tunnel and a more efficient search strategy as co mpared with injured mice. This difference was not due to visuomotor deficit s, as all mice performed equally well in a cued version of the same task. T hese results demonstrate spatial learning impairment following CCI injury i n a task that offers an efficient alternative to the water maze.