Controlling the Urge to Bite: A Computational Analysis of the Role of the Medial Preoptic Area and Ventromedial Hypothalamus Shell in Modulating Aggression and Aggression-Seeking Behavior in Mice

Abstract

Aggression is an important behavior that individuals use to protect and compete for territory, mating partners and resources. Motivation for aggression can be enabled through reinforcement learning of aggression reward. In this experiment, aggression and aggression-seeking behaviors were investigated in the medial preoptic area (MPOA) and the ventromedial hypothalamic shell (VMH shell). The MPOA has been previously identified to play a role in aggression, while the VMH shell has also been linked to aggression motivation. Behavior was studied using a nose-poke paradigm in which the resident pokes a port in its home cage for the reward of an aggressive action against a submissive intruder. Distance and speed parameters were analyzed from the nose-poke paradigm. The adeno-associated virus (AAV) containing the gene of channelrhodopsin ChR2 was injected in the MPOA for MCh animals and the VMH shell for SCh. Optogenetic stimulation was performed during the nose-poke experiments using an optic fiber implanted above the VMHvl to stimulate the projecting terminals of MPOA and VMH shell neurons. Behavior was analyzed using DeepLabCut software to estimate animal position. Preliminary data revealed that the MPOA-VMHvl and VMH shell-VMHvl projections are active during two separate timepoints during aggression and aggression-seeking behavior. Stimulation of the MPOA and VMH shell suppressed noseport poke motivation and reduced attack intensity in the interaction phase. Behavioral analysis supports the hypothesis that activity in the MPOA-VMHvl and VMH shell-VMHvl projections play distinct roles in manipulating both aggression and aggression motivation