Project Summary
Interoception, the process by which the body senses its own internal state, is critical to maintaining
homeostasis through the detection of physiological changes that enable the body to adjust to changing
demands. Dysfunction in interoception may lead to erroneous prediction errors concerning these bodily
needs and is increasingly considered to underlie a number of maladaptive behaviors and psychiatric
disorders, including addiction and eating disorders. Despite this, little progress has been made in
identifying the underlying neural circuit mechanisms of interoception because non-verbal subjects (e.g.
animal models) cannot self-report internal states. Here, we propose a novel conceptual behavioral
framework for studying interoception in animal models in order to identify neuronal ensembles that
encode interoception. Moreover, human imaging studies have informed us that interoception relies
critically on an understudied area of the brain, the insular cortex, but the functions and corresponding
projections from the insular cortex subregions (anterior to posterior) have not been well-studied.
Methods that can simultaneously deliver precise information concerning behavior and projections in a
high-throughput way are therefore required. Molecular profiling techniques have been increasingly
useful for identifying cell types that might serves as the link between genes to circuits, but current
techniques have limitations, namely the modality by which the profiling occurs. We therefore also
propose a new transcriptomic molecular profiling technique, called SNAP-TRAP (Simultaneous
Neuronal Activity and Projection – Translating Ribosome Affinity Purification), that enables coincident
profiling of both activity-dependent and projection-specific neuronal markers. We will validate this
technique using a well-defined neural circuit with known molecular markers and behavioral
consequences. We will then apply the methodology to the insular cortex and its role in interoception.
This technique will also enable us to make comparisons of next-generation RNA-sequencing to single-
cell RNA sequencing for the purpose of identifying useful markers for behavioral validation. Lastly, we
will map our findings back onto tissue sections to achieve spatial transcriptomic information. Through
these experiments we hope to achieve a comprehensive transcriptomic map of the insular cortex that
can be precisely delineated according to particular behaviors and projections, and can be used as a
basis for understanding how dysfunction in interoception leads to maladaptive behaviors. The SNAP-
TRAP technique may then be used by the broader neuroscience community in other brain regions and
behavioral tasks to gain insights into the neural underpinnings of complex behaviors and their
associated psychiatric disorders.
