Environmental Context Modulates Habituation of Visually Evoked Defensive Behavior.

The capacity of animals to rapidly and appropriately respond to potential threats is critical for survival. In many species, this involves innate defensive behaviors, such as flight or freezing. However, not all threats are dangerous. Habituation allows animals to filter out irrelevant stimuli and avoid unnecessary energy expenditure. While environmental context is known to modulate behavior in associative learning paradigms, it remains unclear whether this also applies to visually evoked defensive behaviors. Here, we address this question in mice of either sex by examining the role of environmental context on habituation of defensive responses to threatening visual stimuli. We developed a protocol that produces rapid (within minutes) and stable (lasting at least one week) habituation of freezing responses to slowly sweeping visual stimuli resembling an aerial predator moving across the sky. Using this protocol, we tested the impact of environmental context on habituation and found that changing the context significantly and reversibly reduced the expression of habituation. Specifically, freezing was reinstated when mice were tested in a different context from that used during habituation, reaching levels comparable to nonhabituated animals. Freezing returned to habituated levels when mice were retested in the context used during habituation. In summary, our findings demonstrate that environmental context plays a critical role in shaping habituation of visually evoked innate defensive behaviors. These results reveal a previously unrecognized flexibility in this evolutionarily conserved behavior and highlight the importance of context in regulating responses to visual threats.