NEURAL DYNAMICS OF NOVEL THREAT AVOIDANCE LEARNING IN THE MEDIAL PREFRONTAL CORTEX

Learning to appropriately respond to external information predictive of danger is essential for survival. This active threat-avoidance learning involves sensory processing, stimulus-outcome association formation, and behavioral execution. In rodents, the medial prefrontal cortex (mPFC) has been implicated in linking sensory information to appropriate actions during learning, primarily focusing on learned avoidance. However, how the mPFC gradually builds stable representations from flexible cues during long-term learning remains unclear. Here, we developed a novel behavioral apparatus and paradigm for active threat avoidance, combined with miniscope calcium imaging of the mPFC throughout learning. All mice were trained to reach a target zone prior to shock delivery, the location of which was controlled by software, ensuring random, non-repetitive positioning across trials. Following 1 day of habituation and 7 days of training, performance increased to ~80% and remained stable. On day 8 without foot shock, behavioral testing showed that the learned active avoidance memory was highly stable. Fiber photometry and optogenetic inhibition experiments revealed that the mPFC is essential for this flexible active avoidance learning. Miniscope analysis at the single-neuron level showed altered proportions and response amplitudes of trial-start, shuttle-start, and entry-responsive neurons. Future studies will investigate how the mPFC gradually acquires abstract rules and forms stable representations at the population level.