A Dual-Task Paradigm Combining Physical and Cognitive Training in Mice: Application to Aging

Physical Activity (PA) is often associated with better overall health status, especially in older adults. Numerous pieces of evidence indicate that PA would be more beneficial when applied in conjunction with Cognitive Training (CT) either simultaneously (i.e., in Dual-Task [DT]) or sequentially. Nonetheless, the underlying mechanisms of such benefits remain elusive. To help delve deeper into their understanding, we developed a cognitive-motor DT paradigm in young adult mice and subsequently tested its effect in old age. Three groups of young adults C57BL/6J mice (3.5 months of age; n=10/group) were required. They were given cognitive tasks, either alone (Control) or in combination with PA which was administered either sequentially (SeqT group) or simultaneously (DT group). Mice were trained in a touchscreen chamber: first on a Visual Discrimination (VD) learning task, then on its Reversal (RVD) which assesses cognitive flexibility alongside procedural learning. PA was given through a homemade treadmill, designed to fit in the touchscreen chambers and set at 9 m/min. Fourteen months later, we further evaluated the effects of PA administered in both DT and SeqT groups, on the performance of the now 19-month-old mice. When compared to SeqT and control groups, DT mice significantly displayed better procedural learning in both VD and RVD tasks as young adults. In the RVD task, this enhanced performance was associated with both poorer inhibition and motor performance. Finally, in 19-month-old mice, both DT and SeqT mice displayed better motor and cognitive performances than control mice. This new cognitive-motor DT paradigm in mice yields an interesting framework that should be useful for adapting DT training in aging, including providing knowledge on the neurobiological correlates, to get the most out of its benefits.