Neural circuits regulating social dominance implement a strategy predicted by evolutionary game theory.

Area of Science:

• Neuroscience
• Evolutionary Biology
• Animal Behavior

Background:

• Social conflict is crucial for resource access in animals.
• Evolutionary game theory predicts adaptive strategies for conflict.
• Neural underpinnings of aggression and conflict strategies are not fully understood.

Purpose of the Study:

• To identify the neural circuit regulating the decision to flee in male Drosophila during fights.
• To investigate if the onset of defeat follows probabilistic strategies predicted by evolutionary game theory.
• To explore the role of dopamine and internal states in shaping contest dynamics.

Main Methods:

• Identification of a neural circuit involving Tk-GAL4 FruM neurons, mushroom body circuits, PPL1 dopaminergic neurons, and V2 mushroom body output neurons in male Drosophila.
• Manipulation of neural circuit activity (silencing and activation) to observe effects on fighting behavior and defeat onset.
• Analysis of the influence of internal state variables (hunger, motivation) on defeat probability.

Main Results:

• A specific neural circuit, involving inhibition of Tk-GAL4 FruM neurons via the mushroom body, regulates the probabilistic onset of defeat.
• Disrupting this circuit affects defeat onset, while activating it induces rapid defeat.
• Dopamine plays a dual role: PPL1 neurons mediate defeat, while PAM neurons promote winning; internal states modulate defeat probability.

Conclusions:

• Evolutionary game theory strategies for social conflict are implemented at the circuit level in the brain.
• The study reveals a neural computation for regulating aggression based on payoff and internal state.
• This provides direct evidence linking theoretical evolutionary strategies to neural mechanisms controlling aggression.