Prefrontal dopamine circuits are required for active avoidance learning but not fear learning

Abstract

To survive, animals must rapidly learn to avoid predictable threats. Such learning depends on detecting reliable cue-outcome relationships that efficiently drive behavioral adaptations. The medial prefrontal cortex (mPFC) integrates learned information about the environment to guide adaptive behaviors1-7 and is critical for threat avoidance8-15. However, as most studies have focused on well-learned threat avoidance strategies, the specific inputs that signal avoidability and drive rapid avoidance learning remain poorly understood. Dopamine (DA) inputs from the ventral tegmental area (VTA) potently modulate prefrontal function and are preferentially engaged by aversive stimuli16-21. Previous studies implicated VTA and prefrontal DA in aversive learning22-25, but their findings have been constrained by limited spatiotemporal resolution. Here, we used high-resolution tools to dissect the role of the VTA-mPFC DA circuit in rapid avoidance learning. Optogenetic suppression of VTA DA terminals in mPFC selectively impaired learning of a cued avoidance response, without affecting cue-shock association learning, reactive escape behaviors, or expression of previously learned avoidance. Using a fluorescent DA sensor, we observe rapid, event-locked DA activity that emerged transiently during the initiation of learning. Increased DA encoded aversive outcomes and their predictive cues, while decreased DA encoded their omission and predicted how quickly mice learned to avoid. In yoked mice lacking control over shock omission, these dynamics were largely absent. Together, these findings demonstrate that the VTA-mPFC DA circuit is necessary for rapid acquisition of proactive avoidance behaviors and reveal transient event-related DA signals that underlie this form of learning.