The Impact of Social Isolation on Cognitive Performance in Marmoset Monkeys

Disruption of social relationships is among the biggest factors contributing to poor health and well-being. One of the major neuroregulatory pathways associated with physiological and behavioral responses to stressors is the hypothalamic-pituitary-adrenal (HPA) axis. In response to a stressor, the hypothalamus secretes corticotrophin- releasing hormone (CRH), which mediates the release of adrenocorticotropic hormone into the bloodstream. This leads to the release of glucocorticoids (e.g., cortisol), which is a key component in the physiological stress response . One specific area of health outcomes that has received less attention is the association between stress and age-related changes in cognitive function. Marmosets are a well-suited model to address this question because individuals form strong social pair bonds, exhibit complex cognition, and as a result exhibit similar impaired physiological and behavioral functioning as humans do in response to induced periods of social isolation. The goal is to address the link between social stress and cognition in three keyways. 1) Investigate how marmosets perform on a standard cognitive learning task in response to a social isolation stressor in marmosets. 2) Examine the role of the HPA axis in mediating this effect by blocking the CRH hormone that is released in response to stressors. 3) examine whether these effects are consistent or divergent across different age groups of marmosets including middle and old-aged marmosets. The overarching goal of this project is to investigate the extent to which chronic social isolation effects the learning ability of adult and old-aged common marmoset monkeys utilizing a standardized reversal learning task while manipulating HPA function via treatments with a CRH antagonist (blocks CRH function). Chronic social isolation reflects prolonged stressors which more appropriately models stress-induced deficits in cognition seen in mental health compared to an acute stressor