Normal aging in primates often leads to impaired cognitive function, particularly in working memory (WM), which begins to decline in middle-age. Cognitive changes correlate with structural and functional changes to neurons and white matter pathways in the prefrontal cortex (PFC), a brain area that is a key player in WM. However, we currently lack a mechanistic understanding of how the changes at the single-cell and pathway level impact network function and thus WM performance. Moreover, the prefrontal cortex is only one node in a distributed network of brain regions that contributes to WM, and aging also alters these other –particularly fronto-parietal and visual– areas and long-range inter-areal connections. The central goal of this project is to advance our understanding of the computational and neural mechanisms underlying WM as well as the age- related changes to this executive function in the rhesus monkey model of normal aging. Specifically, we will test the hypothesis that WM arises through coordinated interaction of visual and fronto-parietal brain regions, and that aging-related decline in WM results from changes to both local circuit dynamics and inter-area communication. Our interdisciplinary approach will combine psychophysical, anatomical and physiological experiments with theory and computational modeling, taking advantage of the complementary expertise of the collaborating laboratories. The proposed research has the following specific aims: Aim 1: Identify aging effects on individual neurons, white matter pathways and resting state fMRI activity in fronto-parietal and visual cortices. Aim 2: Develop a multi-area computational neural network model in which WM function emerges from interacting distributed circuits. Aim 3: Model-based interpretation and experimental validation of the neuronal mechanisms underlying age-related WM decline.