Neural circuits of innate social behaviors
Innate social behaviors, including mating, fighting, and parenting, are generated by developmentally hardwired circuits. These circuits mainly reside in subcortical regions and are highly conserved across species (read our review). One main goal of our research is to identify the brain regions and molecularly defined populations in these regions that are essential for the generation of innate social behaviors. Through our works in the last decade, we have identified pVMHvl, PA, LS, and PAG as key regions for generating or inhibiting aggression, aVMHvl for social defense, PA Esr1 for male sexual behaviors, VMHvll CCKAR cells for mediating female sexual behaviors, MPOA Esr1 cells for driving maternal behaviors, and VMHdm SF1 cells for promoting predator defense. We are continuing our circuit dissection effort towards a comprehensive understanding of the neural blueprints of social behaviors.
Innate yet flexible: plasticity of social behaviors
Although animals can innately mate, fight and care for the young, the tendency to express these behaviors varies drastically over experience, context, and internal states (read our review). For example, virgin male and female mice often ignore or even kill infants while mothers and fathers exhaust themselves to care for the young. The dramatic and qualitative change in pup-directed behaviors must be supported by changes in the underlying neural circuits, but how? For another example, winning and losing effects are widely observed across species; that is, the readiness of an animal to fight increases with repeated winning and decreases with repeated losing. How does fighting experience alter the aggression circuit to influence future behaviors ultimately? Additionally, after losing a fight, when the defeated animal reencounters the winner, it quickly runs away from it to avoid losing again. How does the circuit process the aggressor cue differently so that the loser switches from social approach to avoidance? Many of our ongoing research projects are aimed at addressing these questions, elucidating the molecular, hormonal, structural, synaptic, and cellular mechanisms that enable the incredible plasticity of innate social behaviors.
We apply a variety of circuit probing tools, including viral tracing, optogenetics, pharmacogenetics, pharmacology, multi-fiber photometry, two-photon imaging, in vivo electrophysiology, slice recording, molecular engineering, RNA sequencing, immunohistochemistry, and computational modeling. We start each project with an interesting biological question and use whatever necessary tools to get to the bottom of it.