Hippocampal representations of possible futures predict motor output in the superior colliculus

The ability to represent possible futures allows animals to evaluate different options and act accordingly. The hippocampus can express representations of possible future paths, but the brain structures involved in transforming these representations into actions remain unknown. Here we show that hippocampal representations of possible future paths predict motor-related activity in the superior colliculus (SC), a midbrain structure involved in turning. By recording simultaneously from hippocampal neurons and from left- or right-preferring "turn cells" in the motor layers of the SC in navigating mice, we found that hippocampal representations of possible left or right future paths predicted increased firing rates of SC turn cells with matching left or right turn preference. This relationship was also evident in the animals' behavior: when the hippocampus represented future paths that were not ultimately taken, movement trajectories were nonetheless biased toward those paths, as if animals partially enacted possible futures that were represented but not selected. These results reveal a coordination between a cognitive and a motor structure and provide a potential pathway for mental simulations of possible futures to influence actions.