Discussion
Conspecifics constitute emotionally salient stimuli. Furthermore, socio-sexual reward and aggressive- dominant aversion are largely independent of homeostatic states such as hunger and thirst, rendering them more amenable to experimental study than the physical stimuli of food and water. In the present study of male mice, we demonstrate that: (1) The intermediate-to-posterior BA contains a relatively high number/density of glutamate neurons projecting to intermediate NAc core/shell. (2) Approximately 15% of int-BA-NAc neurons are activated by interaction with a (pro-)estrous female and 17% by interaction with an aggressive-dominant male, whereas for post-BA-NAc neurons it is 8% and 13%, respectively. (3) Using TRAPing, successive SR-SA or SA-SR exposure identified that the majority of int-BA-NAc neurons activated by SR are not activated by SA, and vice versa, i.e. the majority of int-BA-NAc neurons are monovalent with respect to the social stimuli investigated. (4) Using GCaMP6 fibre photometry of an int-BA-NAc neuronal population, it could be demonstrated that they are engaged during both distal and proximal interactions with SR. These findings advance current understanding of how emotional stimulus processing by BA-NAc glutamate neurons is organized in the mouse.