Social vulnerability and health determinants of Intrinsic Capacity in Mexican older adults: Evidence from the Mexican Health and Aging Study round 2021.

Innate predispositions powerfully shape how animals approach their ethological tasks (–), but they can also learn new ways to do better when conditions call for improvement (, ). However, the neural mechanisms behind learning as studied in most laboratory operant tasks are typically framed just in terms of making new associations by reinforcing success or punishing failure (), while the role of any predispositions for guiding actions are typically ignored. This leaves open questions about the neural mechanisms by which animals decide to follow their predisposed plan or adopt a newly learned strategy for action, which occurs naturally in many ethological behaviors. For example, homing pigeons innately use their internal compass to navigate but, with experience, can also follow human highways as a reliable way to fly home (). Animals from birds to monkeys instinctively use a win-stay strategy to forage from previously successful sites but can shift their strategy flexibly depending on context to seek better outcomes (–). While there has been much work across species on the neural basis of decision-making in various paradigms (–), we know little about neural mechanisms as one learns from scratch to displace a predisposed decision strategy with a more efficient one. In these natural behaviors, different strategies for choosing specific actions can still lead to the same rewarding outcome, albeit with differential efficacy or reliability, but that is not usually the case for studies of learning in laboratory decision-making paradigms, which instead strictly regulate stimulus-response-outcome contingencies to force changes in actions (, ). In the natural case, to reap the efficiency benefits of finding a strategy better than the predisposed one, animals must learn that new cues are informative (e.g., pigeons identifying highways) even as they initially follow their predisposed strategy and then must decide when to switch away from their instinctive plan of action. Such a transition presumably involves sensory cortical plasticity to represent the new cues associated with reward (, ), but where the neural correlate of the predisposed strategy lies and what happens to it during the course of a switch in strategy is unknown. Here, we use a natural parenting behavior in rodents to investigate how animals switch from a default behavior to adopting a better strategy with experience (). Female mice are intrinsically motivated to search for displaced pups to retrieve (). Their initial search strategy is to return to where they remember last finding a pup (–)—a spatial win-stay strategy for this social behavior (). Females can learn to use natural pup sounds () and even artificial ones to guide their search more efficiently (). We exploited this ethological behavior to model in a domain-general fashion the decision-making process during the transition from the predisposed win-stay to a new search strategy based on a sound cue predicting where a pup will be found.