Summary:
The sense of smell in the mouse largely occurs through the main olfactory system (MOS) which
has the amazing ability to detect trace amounts of an infinite variety of volatile organic ligands.
With this sensory power why does the mouse, and most terrestrial vertebrates, also have a
vomeronasal organ (VNO)? Some think that since the VNO was lost during human evolution it is
not important to study. First, we expect investigating the VNO will further advance our
understanding of all types of chemosensation. The presence of a robust VNO across
evolutionary diverse species indicates that taste and smell have functional blind spots that the
VNO is filling. Understanding the VNO will enable us to know if humans are missing an animal
superpower and can search for ways to augment our sensation, or if we evolved beyond its
tether; perhaps losing this system partially accounts for our remarkable behavioral flexibility.
Second, as an experimental model, the VNO provides unprecedented access to activate and
study circuits critically important to humans. VNO mediated behavior has accelerated
identification of neurons, circuits, and the brain network that underlies mouse social behavior
and provides mechanistic insight to analogous circuits implicated in human social behavior.
Anatomically, accessory olfaction has direct and privileged access to the social behavior brain
network and genetic ablation of this system results in aberrant, dysfunctional social
communication. Although humans are not thought to use olfaction to access social behavior
circuits, the downstream network is critical and dysfunction leads to autism, ADHD, anxiety, or
depression, but much is still unknown. Upon successful completion of this research, we will
have created datasets quantitatively detailing and simultaneously bridging major unknowns
about the accessory olfactory system: what it senses, metrics of neural activity encoding the
environment, and properties of sensory coding in relationship to behavior. Together, our
proposed work will investigate properties of VNO sensation that are expected to differ and
complement the function of the MOS. Our method enables us to gain first insight about evoked
sensory activity in relationship to the environment and behavior during dynamic natural behavior
and is expected to generate new insight about chemosensory function.