Evaluating aged mice in three touchscreen tests that differ in visual demands: Impaired cognitive function and impaired visual abilities

Normal aging is often accompanied by reductions in cognitive abilities as well as impairments in visual acuity in men and mice. In preclinical models of human cognition this concomitance can make it difficult to assess the relative contributions of declined vision and cognitive ability on behavioral measures of cognition. To assess the influence of age on cognition and the impact of visual decline on the performance of touchscreen-based behavioral paradigms in mice, aged (11, 12, 16, 17, 19 and 21 months old) male C57BL/6J mice were compared to young (3 or 4 months old) male C57BL/6J mice using three tests of cognition as well as an assessment of visual acuity. Performance of a Visual Discrimination, Spatial Reversal, and an Automated Search Task were all affected by age. However, there was no relationship between reduced visual acuity and the observed performance impairments. Moreover, the visual acuity of animals with profound cognitive impairments overlapped with those showing normal cognitive ability. Despite the potential confound of impaired visual ability, it appears that the touchscreen approach might be particularly effective in studying age-related cognitive decline. This approach will increase the utility of aged mice as a model of decreased cognitive flexibility and may be particularly important for the study of age-related disorders such as Alzheimer's disease.