The three-panel runway maze adapted to Microcebus murinus reveals age-related differences in memory and perseverance...

Microcebus murinus, a mouse lemur primate appears to be a valuable model for cerebral aging study and for Alzheimer's disease model since they can develop beta-amyloid plaques with age. Although the biological and biochemical analyses of cerebral aging are well documented, the cognitive abilities of this primate have not been thoroughly characterized. In this study, we adapted a spatial working memory procedure described in rodents, the sequential choice task in the three-panel runway, to mouse lemurs. We analyzed the age-related differences in a procedural memory task in the absence or presence of visual cues. Sixty percent of young adult and 48% of aged lemurs completed the exploratory, choice habituation and testing phases at the beginning of the procedure. Young adult lemurs showed a higher level of perseverative errors compared with aged animals, particularly in the presence of visual stimuli. Over trials, old animals made more reference errors compared to young ones that improved quickly their performances under random level. No significant improvement was observed in young adults and old ones over sessions. This study showed that behavioural performances of M. murinus assessed on the sequential choice task in the three-panel runway markedly differ from the previously reported abilities of rodents. The behavioural response of young adult lemurs was influenced by novelty-related anxiety that contributed to their performance in terms of perseverative errors. Conversely, aged lemurs showed less perseverative errors, a rapid habituation to the three-panel runway maze, but made more memory errors. Overall, these findings demonstrate the feasibility to use the three-panel runway task in assessing memory performance, particularly in aged mouse lemurs.