Latent learning without map-like representation of space in navigating ants

Desert ants are excellent navigators. Each individual learns long foraging routes meandering between the trees and bushes in their natural habitat. It is well-known how the insect brain memorizes and recognizes views, and how this recognition can guide their way. However, little is known about the rule that guide spatial learning in the first place. Here we recorded the paths of desert ants navigating in their natural habitat under various displacement conditions. We demonstrate that ants learn continuously the routes they travel and memorize them in one trial, without the need for reward or punishment, and even if these routes are meandering and do not lead to places of interest: a concept called "latent learning", which is typically associated with the formation of map-like representation in vertebrates. Yet, the failure of ants to solve simple artificial navigation tasks -even with the goal being clearly visible- reveals that they relied on egocentric visual memories without map-like representation of the surrounding space. Our results unveil the rules governing the formation and recall of latent memories. A model shows that it can be implemented in the insect's Mushroom bodies brain area through dynamic interactions between short- and long-lasting memories.