This transformative award application is designed to test an integrative hypothesis about astrocyte
function across the brain while extending the current limits of state-of-the-art technologies in cellular imaging
and spatial transcriptomics. The team of investigators with cellular, molecular, systems,
theoretical/computational neuroscience and biomedical engineering expertise will take a multipronged
approach to test the central hypothesis that astrocytes serve the function of integrating neuromodulator
signals in circuits across the brain.
Astrocytes are by some accounts the most common cell in the brain. They have been historically
viewed as support cells for neural circuits, but emerging evidence suggests that they are active participants in
circuit functions. This is especially interesting because astrocytes are affected by stress, aging, and many
diseases of the central nervous system. Remarkably, astrocytes express receptors for serotonin,
norepinephrine, dopamine, and acetylcholine; the four neuromodulator systems that arise from deep structures
and innervate most brain circuits. These neuromodulator systems have considerable overlapping circuit
functions suggesting that a mechanism for integrating their inputs is important for disambiguating how each
neuromodulator exerts its contribution to the circuit functions. This project will test the possibility that
astrocytes provide such an integrator function.
The investigators will use state of the arts techniques and develop new ones to test how astrocytes are
affected by neuromodulators and how these effects impact circuit functions and behavior in two brain
systems. In vivo studies will test the hypothesis on a cell population level manipulating each of the
neuromodulator circuits while testing astrocyte responses to all four, circuit physiology, and behavior. Ex vivo
studies will focus on single cell differences in astrocytes by combining functional studies that parallel in vivo
ones. These spatially resolved functional studies will be aligned with spatial single cell transcriptomics
providing gene expression data to parallel functional data at scale. Stress and aging are known to impact
astrocytes and neuromodulator functions and adversely affect many neuropsychiatric diseases. The team will
lastly establish how stress and aging impact the ability of astrocytes to integrate neuromodulator signals using
their cutting edge techniques.
Completing these ambitious studies will unequivocally test a transformative idea for an
organizing principle around astrocyte function throughout the brain and inform how dysfunction of these
cells can be contributing to diseases of the central nervous system.