Project 3: Dissecting the neural and neuromodulatory control mechanisms of arterial dynamics during sleep

Abstract, Project 3 Sleep is accompanied by large changes in neural activity, modulatory state, and hemodynamics. The large arterial dilations and contractions during sleep could drive perivascular pumping of CSF, which would help clear fluid and solutes from the brain. We hypothesize that during NREM sleep, the large oscillations of arterial diameter are driven by local neural activity and coordinated globally across the cortex by noradrenergic (NE) and cholinergic (ACh) neuromodulatory drive. We will test this idea by optically imaging the cortical vasculature of sleeping mice while perturbing neural activity and neuromodulation. In Aim 1, we will alter the activity of defined neuronal populations during sleep using opto-and chemogenetic tools to determine the role of local neural activity in controlling vascular dynamics. In Aim 2, we will use fluorescent biosensors, optogenetics, and chemogenetics to understand the role of cholinergic and noradrenergic modulation in coordinating the global cortical vascular dynamics during sleep. We will measure the temporal relationship between ACh and NE modulation, and dissect their respective roles in controlling hemodynamics during sleep. In Aim 3, we will use multiplane two-photon imaging to visualize the directions of propagation of arterial constrictions and dilations and widefield imaging of neural and vascular signals to visualize how vascular activity is coordinated across multiple spatial scales during sleep. Project 3 will contribute to the overall U19 proposal by dissecting the neural mechanisms controlling arterial dilations and constrictions during NREM sleep. Our measures of arterial dynamics at both the local and global scales during sleep will provide important data for the modeling in Project 1. Our use of the mouse model will complement the measurements in Project 2. It will also help bridge the detailed mechanistic studies relating arterial diameter changes of CSF movement in Project 2 with the other Projects by making corresponding arterial dynamics measures during sleep. Our determination of causal relationships among neuromodulation, neuronal subtype activity, and vascular dynamics will be applied to understand the simultaneous EEG and neuroimaging data in Project 4.