Background

Animal models are critical for developing a better understanding of human memory function and dysfunction. Early animal studies examining memory dysfunction reported the critical importance of the hippocampus and surrounding cortical regions within the medial temporal lobes (Winocur, 1990; Zola-Morgan and Squire, 1990; Squire et al., 2001). One area of memory function that has been found to be particularly dependent on the hippocampus is spatial memory formation and retrieval. Many of the spatial memory tasks which are most sensitive to hippocampal damage or disruption are those that involve navigation, such as the radial arm maze, Barnes maze, and Morris Watermaze (Clark et al., 2007). Although such tasks are valuable, there are some limitations and potential confounds in using tasks that require navigation. For example, certain populations may have difficulty in navigating, but can still form and retrieve spatial memories. In addition, the performance aspect of navigation, independent of the spatial memory, may require the recruitment of additional brain areas. Therefore, it is important to have tests of spatial memory that are non-navigational. The DOR task provides a means for assessing spatial memory recognition without the animal having to navigate to a learned reference location in order to express the memory.