Grant: Project Grant

Approximately 10% of Canadian adults will experience major depression at some point in their lives. One of the core symptoms of this psychiatric disorder is a pronounce absence of pleasure in most activities. This research proposal seeks to identify neural circuit activity that promotes the sensation of pleasure. We focus on one very specific cause of pleasure, the consumption of highly palatable food. The pleasure derived from eating, at least as measured by positive facial reactions in rodents, can be driven by mu opioid receptor signaling in a particular forebrain area: the rostral nucleus accumbens shell. In humans, neural activity in this region correlates with the pleasures of food, sex, addictive drugs, music, and art. Mu opioid receptor signaling here is believed to alter the balance of activity between different types of output neurons, but the details and mechanisms of this effect are unknown. The principal aim of this grant is to identify in rodents how positive facial reactions to food consumption arise from mu opioid receptor signaling in the nucleus accumbens. We will use a combination of tools to record and manipulate specific cell types and circuits to identify what specific balance of activity in this area is the cause of mu opioid receptor-induced positive facial reactions to feeding. We will also try to enhance positive feeding reactions in an enduring manner through long lasting circuit manipulations. A better understanding of this particular source of hedonic reactions will provide a framework for a more general understanding the neural underpinnings of pleasure. Insights gained from these kinds of circuit analyses have already been used in the development of highly specific therapeutic interventions designed to improve the lives of patients afflicted by mental illness.