Rank- and threat-dependent social modulation of innate defensive behaviors

Fear and defensive behaviors are crucial survival mechanisms in group-living animals, with social context playing a significant role in shaping these responses. The study explored how dominance hierarchy influences innate fear in mice exposed to two naturalistic threats: a brief visual looming stimulus and a persistent predatory threat from a live rat.

The findings revealed that social presence ameliorated threat-induced stress and altered defensive behaviors in a rank and threat-dependent manner. During looming exposure, the presence of others reduced immediate defensive reactions and lessened post-looming anxiety, with dominant mice reaping the most advantages. Similarly, during rat exposure, social context prompted a transition from passive to active defense strategies, once again favoring dominant individuals.

These behavioral shifts were associated with a reorganization of defensive state transitions, illustrating that dominance hierarchy dictates both the manifestation and timing of innate defensive behaviors. Conversely, threat exposure intensified social engagement, with dominant mice showing more proactive social interactions and subordinates responding more readily to dominant social cues.

In summary, this research demonstrates how dominance hierarchy modulates defensive responses to various naturalistic threats and highlights the reciprocal relationship between threat experience and social behavior, laying the groundwork for investigating the neural basis of socially modulated innate fear.