DOPAMINERGIC REGULATION OF HIPPOCAMPAL VALUE PROCESSING DURING DECISION MAKING

Accumulating evidence indicates that the hippocampus contributes to value-based decision making in addition to its established roles in spatial and episodic memory. Although we previously showed that dorsal CA1 encodes value-related signals and is involved in value learning, how such signals are regulated remains unclear. Here we investigated the role of hippocampal dopaminergic signaling in value-based decision making.
Mice performed a dynamic foraging task while hippocampal dopamine signaling was manipulated pharmacologically and optogenetically. Local blockade of either D1 or D2 dopamine receptors reduced choices toward higher-reward-probability targets and decreased reward acquisition. Reinforcement learning analyses revealed that D1 receptor blockade selectively impaired value learning by reducing the learning rate.
To causally test the contribution of dopaminergic input, we optogenetically inhibited projections from the ventral tegmental area to the hippocampus. This manipulation similarly reduced high-value choices. Temporally specific inhibition revealed dissociable effects across task epochs: pre-choice inhibition induced an ipsilateral choice bias, whereas outcome-period inhibition selectively impaired value updating.
Together, these results demonstrate that hippocampal dopaminergic signaling contributes to value-based choice and learning, with dissociable effects across task epochs. Our findings suggest that dopamine modulates hippocampal value processing across distinct phases of decision making.