Federico Claudi

Highlights • GABAergic neurons in the dorsal PAG fire action potentials tonically • They provide a major source of synaptic inhibition to excitatory PAG neurons • Tonic GABAergic activity in the PAG sets a threshold for instinctive escape • PAG GABAergic neurons control both escape initiation and termination Summary Escape behavior is a set of locomotor actions that move an animal away from threat.

Abstract To avoid predation, animals perform defensive actions that are both instinctive and adaptable to the environment. In mice, the decision to escape from imminent threats is implemented by a feed-forward circuit in the midbrain, where excitatory VGluT2+ neurons in the dorsal periaqueductal gray (dPAG) compute escape initiation and escape vigour from threat evidence.

17 Richard R. Sutton A.G.B. Reinforcement Learning - An introduction. The MIT Press, ) models were trained to navigate a grid world representation of the Arenas 2, 3 and 4 from the experimental study. All RL simulation, analysis and data visualization work were done in custom Python code. The grid world representation of Arena 4 consisted of a 50x50 array of quadrilateral cells with zeros corresponding to locations on the arena (126 cells in total) and ones to locations inaccessible by the agent.