Children with an extremely inhibited, anxious temperament (AT) are at increased risk for anxiety disorders and depression. Using a rhesus monkey model of early-life AT, we previously demonstrated that metabolism in the central extended amygdala (EAc)—including the central nucleus of the amygdala (Ce) and bed nucleus of the stria terminalis (BST)—is associated with trait-like variation in AT. Here, we use fMRI to examine relations between Ce-BST functional connectivity and AT in a large multi-generational family pedigree of rhesus monkeys (n = 170 females and 208 males). Results demonstrate that Ce-BST functional connectivity is heritable, accounts for a significant but modest portion of the variance in AT and is co-heritable with AT. Interestingly, Ce-BST functional connectivity and AT-related BST metabolism were not correlated and accounted for non-overlapping variance in AT. Exploratory analyses suggest that Ce-BST functional connectivity is associated with metabolism in the hypothalamus and periaqueductal gray. Together these results suggest the importance of coordinated function within the EAc for determining individual differences in AT and metabolism in brain regions associated with its behavioral and neuroendocrine components. SIGNIFICANCE STATEMENT Anxiety disorders directly impact the lives of nearly 1 in 5 people, accounting for substantial worldwide suffering and disability. Here, we use a nonhuman primate model of anxious temperament (AT) to understand the neurobiology underlying the early-life risk to develop anxiety disorders. Leveraging the same kinds of neuroimaging measures routinely used in human studies, we demonstrate that coordinated activation between the central nucleus of the amygdala and the bed nucleus of the stria terminalis is correlated with, and co-inherited with, early-life AT. Understanding how these central extended amygdala regions work together to produce extreme anxiety provides a neural target for early-life interventions with the promise of preventing life-long disability in at-risk children.

Non-human primate (NHP) models are essential for developing and translating new treatments that target neural circuit dysfunction underlying human psychopathology. As a proof-of-concept for treating neuropsychiatric disorders, we used a NHP model of pathological anxiety to investigate the feasibility of decreasing anxiety by chemogenetically (DREADDs) reducing amygdala neuronal activity. Intraoperative MRI surgery was used to infect dorsal amygdala neurons with AAV5-hSyn-HA-hM4Di in young rhesus monkeys. In vivo microPET studies with [¹¹C]-deschloroclozapine and postmortem autoradiography with [³H]-clozapine demonstrated selective hM4Di binding in the amygdala, and neuronal expression of hM4Di was confirmed with immunohistochemistry. Additionally, because of its high affinity for DREADDs, and its approved use in humans, we developed an individualized, low dose clozapine administration strategy to induce DREADD-mediated amygdala inhibition. Compared to controls, clozapine selectively decreased anxiety-related freezing behavior in the human intruder paradigm in hM4Di-expressing monkeys, while coo vocalizations and locomotion were unaffected. These results are an important step in establishing chemogenetic strategies for patients with refractory neuropsychiatric disorders in which amygdala alterations are central to disease pathophysiology.