Conjoint generalized and trajectory-specific coding of task structure by prefrontal neurons

Neurons in the medial prefrontal cortex (mPFC) are spatially tuned. Trajectory-specific firing with distinct spatial tuning on different paths to reward sites as well as generalized spatial tuning with similar responses on separate trajectories have been described. However, it is unclear whether such distinct populations contribute differently to the encoding of task space. Here, we find coexisting populations of neurons with trajectory-specific and generalized tuning profiles in an olfaction-guided spatial memory task in mice. Neurons with generalized representation show stable spatial tuning within and across days, allow accurate predictions of the animal's position, and preferentially emerge upon task learning. In contrast, cells with trajectory-specific spatial tuning display dynamically changing tuning functions, are less informative about the current position, and can be identified at a larger proportion early in task learning. These results highlight a role for neurons with generalized tuning in the efficient and stable representation of task space.