In naturalistic environments, animals navigate in order to harvest rewards. Successful goal-directed navigation requires learning to accurately estimate location and select optimal state-dependent actions. Midbrain dopamine neurons are known to be involved in reward value learning. They have also been linked to reward location learning, as they play causal roles in place preference and enhance spatial memory. Dopamine neurons are therefore ideally placed to provide teaching signals for goal-directed navigation. To test this, we imaged dopamine neural activity as mice learned to navigate in a closed-loop virtual reality corridor and lick to report the reward location. Across learning, phasic dopamine responses developed to visual cues and trial outcome that resembled reward prediction errors and indicated the animal’s estimate of the reward location. We also observed the development of pre-reward ramping activity, the slope of which was modulated by both learning stage and task engagement. The slope of the dopamine ramps was correlated with the accuracy of licks in the next trial, suggesting that the ramps sculpted accurate location-specific action during navigation. Our results indicate that midbrain dopamine signals, through both their phasic and ramping activity, provide teaching signals for improving goal-directed navigation.
bioRxiv Subject Collection: Neuroscience