The multi-stage plasticity in the aggression circuit underlying the winner effect.

Area of Science:

• Neuroscience
• Behavioral Biology
• Aggression Research

Background:

• The
• winner effect
• describes how winning increases future success and aggression.
• The neural mechanisms underlying this phenomenon are not fully understood.

Purpose of the Study:

• To investigate the neural plasticity associated with the winner effect in male mice.
• To identify the specific changes in the aggression circuit during prolonged winning.

Main Methods:

• Utilized a 10-day winning paradigm in male mice.
• Employed optogenetics to manipulate and study neural pathways, specifically the posterior amygdala (PA) and ventrolateral part of the ventromedial hypothalamus (VMHvl).
• Measured synaptic potentiation and neuronal excitability.

Main Results:

• Winning induced a transition from target-specific to generalized aggression enhancement.
• Observed three distinct stages of plasticity in the VMHvl: potentiation of excitatory inputs, transient local connectivity strengthening, and delayed excitability increase.
• Demonstrated that PA-VMHvl pathway potentiation is critical for triggering these plasticity events and that blocking it prevents winning-induced changes.

Conclusions:

• The winner effect involves complex Hebbian synaptic and excitability plasticity within the aggression circuit.
• These neural adaptations contribute to the increased aggressiveness observed in repeated winners.
• The PA-VMHvl pathway plays a crucial causal role in mediating the neural effects of winning.