Parvalbumin-expressing interneurons in prelimbic cortex regulate social bonding

Although much is known about the neuroanatomy of social behavior, still the functional circuitry of kinship is poorly understood. As some studies indicate a crucial role of the activity of prefrontal cortex in social attachment, we investigated the effects of the cell-specific induction of inhibition in its prelimbic part (PL). Specifically, we artificially activated parvalbumin(PV)-expressing inhibitory neurons in the PL and evaluated its influence on mouse bonding behavior and interest in familiar social stimuli.

Animals were tested in Eco-HAB, an ecologically relevant, RFID-based system for assessment of sociability in group-housed mice. Eco-HAB enables continuous, individualized measurement of voluntary social behavior in an environment unconfounded by the presence of humans. Using genetically modified mice selectively expressing Cre protein under the PV promoter combined with the PSAM/PSEM chemogenetic approach, we performed a time-constrained, cell-specific stimulation of the PV neurons in the PL and tested subjects social behavior in the Eco-HAB during the 90-minute period following the systemic administration of the PSEM. Furthermore we also examined if activation of the PV cells interrupts social learning about reward or punishment. To that end, mice were tested in the IntelliCage system, which enables automated assessment of cognitive abilities in group-housed rodents.

We show that PL-constrained chemogenetic excitation of the PV neurons impairs in-cohort sociability and reduces interest in familiar social stimuli. Notably, such manipulation of neuronal activity does not alter approach to novel social stimuli and social learning, indicating distinctive mechanisms for expression of kinship.

Our research reveals a specific role of the PV cells in the PL in maintenance of social structure and in sustaining ongoing interest in familiar conspecifics. Thus, presented data lays foundation for understanding neural underpinnings of social attachment.