Project Summary Decades of correlational research have revealed that a person’s ability to integrate physiological information from the body and sense or experience those physiological signals, a process known as interoception, is critical to health and deteriorates across the lifespan, even in healthy aging. Understanding the mechanisms that mediate interoceptive processes is therefore critical for developing treatments and interventions for a broad array of interoception-related diseases and aging-related processes. Such mechanistic investigations require the capacity to causally manipulate potential neurobiological and environmental substrates of interoception, which necessarily requires an animal model. In the proposed work, we develop a highly translatable animal model of interoception by developing a behavioral task to evaluate cardiac interoceptive ability in rhesus monkeys (Macaca mulatta) and then by developing a behavioral task that indexes the extent to which monkeys use cardiac interoceptive signals to guide affect-related cognition. We also examine how individual variation in cardiac function relates to variation in interoceptive ability to establish functional homologies between monkeys and humans. This innovative work will be the first to use a translatable measurement of cardiac interoceptive ability in nonhuman animals and sets the stage for further mechanistic investigations to understand how and why interoception changes across the lifespan and in a variety of diseases ranging from mood disorders to neurodegenerative disorders like Alzheimer’s disease. Ultimately, understanding the biological mechanisms of interoception is necessary to develop treatments and interventions for interoception-related diseases and to promote wellbeing across the lifespan.