Hippocampal projections to the ventral striatum: from spatial memory to motivated behavior

Multiple regions of the hippocampal formation project to the ventral striatum, a central node in brain circuits that subserve aspects of motivation. These projections emphasize information flow from the ventral (temporal) pole of the hippocampus and interact with converging projections and neuromodulatory inputs upon arrival in the ventral striatum. Simultaneous neural recordings in the rat show that ventral striatal activity displays intricate timing relationships with the hippocampus, spanning multiple timescales and behavioral states, such as theta phase precession during reward approach and reactivation of place-reward associations during sleep. Disconnection of the hippocampus and ventral striatum results in impairments in the use of spatial information for place preference, as well as in location-appropriate responding to reward-predictive cues. Together, these findings indicate that spatial and contextual information from the hippocampus shapes reward-predictive activity in the ventral striatum, which in turn contributes to the learning and expression of place-reward associations.