The ventral hippocampus (vHPC) controls emotional response to environmental cues, yet the mechanisms are unclear. Biane et al. examine how positive and negative experiences are encoded by vHPC ensembles, showing that vCA1 does not contain generalized representations of valence but rather discriminates salient stimuli based on their identity and sensory features.

Reinforcement learning (RL) offers a compelling account of how agents learn complex behaviors by trial and error, yet RL is predicated on the existence of a reward function provided by the agent's env...