Event:

In rodents, olfactory investigation is essential to assess the conspecific identity, e.g., familiarity and sex. One of well-studied phenomena in mice and rats is so-called social discrimination or social memory. They "remember" the identity of an individual whom they met recently, and they use the "social memory" to discriminate between familiar and novel individuals, therefore, they prefer investigating a novel one over a familiar one. My PhD-postdoc project was to elucidate the vasopressin system in the rat olfactory bulb (OB) in the context of social discrimination. Vasopressin is a neuropeptide which is known to be related to various social behavior, and a vasopressin receptor antagonist injected into the OB impairs social discrimination. In the OB a subpopulation of glutamatergic neurons expresses vasopressin. Therefore, we investigated how the vasopressin cells (VPC) get activated using an in-vivo paradigm and an electrophysiological patch-clamp recording. We found that VPCs are more activated during interacting with a conspecific, and that acetylcholine modulates the excitability of VPCs. Furthermore, we performed in-vitro electrophysiology and Ca2+ imaging on acute OB slices to investigate how vasopressin modulates neural activity of other OB neurons. We found that vasopressin reduces and increases excitation of projection neurons and inhibitory neurons, respectively. The stronger inhibition of excitatory neurons by vasopressin could lead to a better signal-noise ratio in turn better neural representations in higher brain regions, such as the olfactory cortex that helps discriminate individual olfactory signatures.