A repertoire of foraging decision variables in the mouse brain

In any given situation, the environment can be parsed in different ways to define useful decision variables (DVs) for any task, but the way in which this manifold of potential decision strategies is processed to shape behavioral policies is not known. We recorded neural ensembles in the frontal cortex of mice performing a foraging task admitting multiple DVs. Methods developed to uncover the currently employed DV revealed the use of multiple strategies and latent changes in strategy within sessions. Optogenetic manipulations showed that the secondary motor cortex (M2) is needed for mice to use the different DVs in the task. Surprisingly, we found that, regardless of the DV best explaining the behavior of each mouse, M2 activity reflected a full basis set of computations spanning a repertoire of DVs extending beyond those useful for the present task. This form of multiplexing may confer considerable advantages for learning and adaptive behavior.