Rapid spatial cognition in mice, with and without neocortex and hippocampus

Rapid learning, memory, and generalization are often attributed to the neocortex and hippocampus. We examined these cognitive abilities in mice navigating a reconfigurable 3D labyrinth. Naïve wildtype mice solved a complex route within a few rewards, generalized to similar problems, and learned to favor a decision far removed from reward experience, all within a few hours. Computational modeling suggests that much of the learning occurs even before the first occurrence of reward, as the animal builds a model of the environment. Mutant mice lacking neocortex and hippocampus retain all these cognitive abilities, and remember the task over multiple weeks. Their main deficit is a delay of the learning curve from inefficient exploration. In a few hours of exposure to the task, the subcortical brain has little opportunity to reorganize in response to the challenge. We conclude that rapid spatial learning in mice does not strictly require circuits of the hippocampus or neocortex.