Compulsive eating is a major contributor to the obesity epidemic in the US, as over 35% of adults are now classified as overweight or obese. Behavioral outcomes such as compulsive eating derive from a complex interaction of genetics, innate behaviors and learning about previous experiences. Cue-food associations (e.g. advertising, eating in front of the television, etc.) that are formed during periods of hunger lead to long-lasting memories that control non-homeostatic overconsumption. However, the neural circuitry, and specifically the molecular cell types, governing this behavior are not well defined. Using an original paradigm that induced overconsumption in sated mice with contextual cues, I have established a role of the insular cortex, and specifically Nos1 neurons within the insular cortex, as critical mediators of learned overconsumption. These neurons do not play a role in homeostatic feeding itself and are therefore hypothesized to provide top down control of homeostatic feeding circuitry to control food intake. Moreover, a projection from the insular cortex to the central amygdala is necessary to generate this overconsumption response. Under the primary mentorship of Dr. Jeffrey Friedman at the Rockefeller University and the co-mentorship of Dr. Denise Cai at the Icahn School of Medicine at Mount Sinai, I will continue to build on my behavioral and molecular neuroscience expertise while developing my training in optogenetics and in vivo calcium imaging. In the mentored K-phase of this grant, I will analyze the role of a molecularly defined cortical-amygdalar circuit in overconsumption using optogenetics and calcium imaging techniques. I will also determine the amygdala targets of insular cortex Nos1 neurons. In the independent phase (R00), I will utilize retrograde tracing techniques to examine the regions and molecularly profile the cell types that directly project to the insular cortex neurons that control overconsumption, and test causally how they are functionally involved in non-homeostatic feeding. Together, these data will establish a cell-type specific circuit through the insular cortex that controls overconsumption in response to environmental stimuli. This data will expand the knowledge of higher-order brain regions involved in feeding behavior and may lead to the development of novel therapeutic avenues to control overeating. At the same time, the research and training plans proposed in this application will enable me to develop my technical and professional skills in order to transition to an independent research position. With the successful completion of this project, I will have developed a platform for a fully independent research program aimed at understanding how the brain coordinates the interplay between innate and learned behaviors that drive maladaptive choices.
Environmental cues can serve as powerful conditioned stimuli that alter behavioral choices in both adaptive and maladaptive ways. In particular, cues like television or advertising, that are associated with food, can lead to overeating and weight gain, but the neural circuitry underlying this effect has not been well defined. The research proposed in this grant serve as a general model for how learning and memory modulate innate behaviors and will identify molecularly defined brain circuits that control non- homeostatic eating to aid in the development of treatments for obesity and overeating behaviors.
