A Continual Trials Approach to Recognition Memory in Mice

Abstract

This thesis sought to address and improve resolve some issues surrounding tests of recognition memory in animals. Since these spontaneous object recognition memory tasks are widely used, especially in mice, there is a need to develop a recognition task that would reduce the variability, extend and translate the task to potential areas of neuroscience research.
Study 1 sought to validate the continual trials approach that was originally designed for rats to mice and replicate the findings of Ameen-Ali et al., (2012) in the spontaneous object recognition and object-location task. Study 1 found that performance of mice was comparable to previous studies of object recognition and object location memory, and statistically meaningful results were obtained with approximately 30 – 50 % fewer mice than typically used in the standard one trial a day version of the spontaneous object recognition tasks. Study 2 sought to extend the continual trials apparatus to establish the age-related changes of object recognition and object-location memory in normal ageing mice; and found that ageing mice showed no age-related decline of recognition memory. Study 3 found no evidence of age-related changes of object recognition and object-location memory in a transgenic mouse model of Alzheimer’s Disease, TASTPM mice. In study 4, the continual trials apparatus was adapted to incorporate variable retention delays (by blocking the sample and test phases) and found no evidence of delay-dependent effect on object recognition memory. Study 5 provided novel evidence that NMDA blockade using the MK-801 drug had no effect on object recognition memory in mice when controlled for state-dependency of memory. The key findings of this thesis include the successful validation of the continual trials apparatus in mice and the evidence that studies using reduced number of mice can nonetheless provide valid results in object recognition memory tasks.