BLIND RATS ARE NOT PROFOUNDLY IMPAIRED IN THE REFERENCE MEMORY MORRISWATER MAZE AND CANNOT BE CLEARLY DISCRIMINATED FROM RATS WITH COGNITIVE DEFICITS IN THE CUED PLATFORM TASK

The Morris water maze is commonly used to test cognitive function in r odent models of neurological disorders including age-related cognitive deficits. It is often assumed that the most profoundly impaired aged rats may be blind due to retinal degeneration, and it has been reporte d that animals with visual sensory deficits can be identified based on their performance in a cued platform task. The results of the present study demonstrate that blind rats can perform surprisingly well in th e reference memory version of the Morris water maze, and that blind ra ts cannot be selectively excluded based on performance in the cued pla tform task since atropine-treated rats also perform poorly in the cued platform task. Future studies may be able to develop screening proced ures that help to eliminate subjects with non-cognitive deficits, but the present results do not support the use of the cued platform or str aight swim task as screening procedures. Experimenters must be careful to consider the role that visual sensory function and other non-cogni tive factors may have in performance of the spatial learning Morris wa ter maze, and also the role that severe cognitive deficits may have in performance of the cued platform task.