Takeshi Murai¹, Lauren Mongeau¹, Lauren Bailey¹, Abbey Setlik¹, Stacey J. Sukoff Rizzo^1,2

Episodic memory is one of the long-term memories that involves the recollection of personal experiences or events (“What”), linked directly with the time (“When”) and place (“Where”). This is also one of the earliest cognitive domains that are impaired in age-related neurodegenerative disorders such as Alzheimer’s disease. We have been establishing a comprehensive battery of touchscreen-based tasks in marmosets that captures a spectrum of cognitive domains sensitive to detect aging-related cognitive decline. The present study describes the establishment of a Paired Associates Learning (PAL) test, which has been successfully used to evaluate episodic-like memory in humans. Initially, marmosets are trained on an FR-1 schedule of positive reinforcement using touchscreens mounted to their home cages. For the PAL task, subjects were trained to associate touch with a specific stimulus (“What”) presented in a specific location (“Where”) to receive a reward. Baseline testing presented two unique stimulus-location pairs. Once the subject learned the stimulus-location combinations, they were assessed in probe trials at 1 day, 2 weeks, 4 weeks, 3 months and 6 months of post-training. Our preliminary data demonstrate that marmosets have the ability to retain intact episodic-like memory over time. Interestingly, we observed the earliest decay in episodic-like memory in aged marmosets within 3 months, while younger marmosets retain episodic-like memory beyond 6 months. Ongoing studies continue to evaluate natural decay of episodic-like memory in this task in aged versus young subjects with longitudinal studies planned as annual assessments throughout the subject's lifespan.

¹Aging Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA

²Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA

Funding Support: National Institute on Aging NIA R24AG073190, NIAU19AG074866