Role of brain Avpr1a-expressing neurons in modulation of social behavior - Project Summary
The importance of understanding the neurobiology of social behavior is underscored by the fact that social
interactions permeate nearly every aspect of human life. How we are raised, our interactions with peers,
romantic relationships, parenting our own children. All these relationships impact our quality of life, and atypical
social interactions can have devastating consequences both for individuals and their social networks. The
negative impact of disrupted social behavior can lead to and exacerbate health problems, whereas positive
social interactions and supportive environments can improve health outcomes. Better understanding of neural
mechanisms underlying social behavior, a key objective of strategic goals laid out by the National Institute of
Mental Health, will help identify targets for treatment of underlying causes that disrupt behavior and motivate
new ways of using social interaction itself as a therapeutic intervention to improve health outcomes. Decades
of research have shown unequivocally that the neuropeptide arginine vasopressin (Avp) impacts both pro-
social (e.g., parental care, juvenile play, pair-bonding, and social memory) and anti-social (e.g., aggression and
territorial flank-marking) behaviors in numerous mammalian species, but mechanisms by which Avp impacts
social behavior are not fully understood creating a critical gap in knowledge. Anatomical studies of Avp neuron
projections suggest that Avp producing neurons in the bed nucleus of the stria terminalis (BNST) and medial
amygdala are likely to be involved in the regulation of prosocial behavior given that their targets include brain
regions associated with motivated behavior, emotional state, and reward (e.g., the mediodorsal thalamus, the
target of proposed studies). A central hypothesis is that activation of Avp-responsive (i.e., Avp 1A receptor-
expressing, Avpr1a) neurons in brain regions controlling motivation and emotion promote pro-social behavior
(i.e., increase interest in social stimuli and engagement in non-aggressive behaviors) and decrease anti-social
behavior (i.e., social avoidance and display of aggressive behaviors). To test this hypothesis and discover
underlying mechanisms, 3 Aims are proposed. Proposed experiments make use of a newly characterized
mouse model that allows genetic access to Avpr1a-expressing cells enabling selective targeting and
differentiation between Avpr1a and non-Avpr1a neurons. In Aim 1, electrophysiological, transcriptomic, and
viral tracing strategies will be used to identify the fundamental electrical behavior, gene expression patterns,
and connectivity of mediodorsal thalamus Avpr1a neurons, a previously unexplored neuronal subtype. The
mediodorsal thalamus is a down stream target of the dopamine reward system, is innervated by the BNST Avp
system, and through its projections to the medial prefrontal cortex influences memory, cognitive flexibility, and
decision-making, all critical to the expression of social behaviors. Then, a chemogenetic loss-of-function
strategy will be used to directly assess the role of the mediodorsal thalamus Avpr1a neuron subtype during
social interactions (Aim 2) and tests of cognitive behavior (Aim 3).
