Fig. 1: Experimental design of fear conditioning in a naturalistic setting.

a An illustration of a tethered rat foraging for a food pellet in the open arena (inset shows a headstage and placement of subcutaneous shock wires). b Timeline of experiment. Habituation: Rats were placed in a closed nest with dispersed food pellets for 30 min/day. Baseline: Rats were allowed to leave the nest to discover food pellets placed 25–125 cm (in 25 cm increments from the nest) in the foraging arena. Training: Animals approaching the pellet location experienced a delayed pairing of tone-shock (T-S), tone-owl (T-O), tone/owl-shock (T/O-S), or owl-shock (O-S). Tone Test: On subsequent days, all rats were placed back in the foraging arena and upon nearing the food pellet, the tone was activated. c Schemas of delayed pairings of stimuli. The T-S, T-O, and T/O-S (but not O-S) groups were presented with a tone 5 s before the gate opening that stayed on until the animals were within 25 cm of the food pellet, at which the tone co-terminated with the triggered shock (1 s), owl (1 s,) or owl-shock (100 ms interstimulus interval, ISI) stimuli. d A representative rat in the foraging arena (208 cm length × 66–120 cm expanding width × 61 cm height) during a baseline trial, where the animal successfully acquires the pellet, and during a T/O-S trial, where the animal flees from looming owl and shock into the nest (69 cm length × 58–66 cm width × 61 cm height).