Brain hemodynamics serve as a proxy for neural activity in a range of noninvasive neuroimaging techniques including functional magnetic resonance imaging (fMRI). In resting-state fMRI, hemodynamic fluctuations have been found to exhibit patterns of bilateral synchrony, with correlated regions inferred to have functional connectivity. However, the relationship between resting-state hemodynamics and underlying neural activity has not been well established, making the neural underpinnings of functional connectivity networks unclear. In this study, neural activity and hemodynamics were recorded simultaneously over the bilateral cortex of awake and anesthetized Thy1-GCaMP mice using wide-field optical mapping. Neural activity was visualized via selective expression of the calcium-sensitive fluorophore GCaMP in layer 2/3 and 5 excitatory neurons. Characteristic patterns of resting-state hemodynamics were accompanied by more rapidly changing bilateral patterns of resting-state neural activity. Spatiotemporal hemodynamics could be modeled by convolving this neural activity with hemodynamic response functions derived through both deconvolution and gamma-variate fitting. Simultaneous imaging and electrophysiology confirmed that Thy1-GCaMP signals are well-predicted by multiunit activity. Neurovascular coupling between resting-state neural activity and hemodynamics was robust and fast in awake animals, whereas coupling in urethane-anesthetized animals was slower, and in some cases included lower-frequency (<0.04 Hz) hemodynamic fluctuations that were not well-predicted by local Thy1-GCaMP recordings. These results support that resting-state hemodynamics in the awake and anesthetized brain are coupled to underlying patterns of excitatory neural activity. The patterns of bilaterally-symmetric spontaneous neural activity revealed by widefield Thy1-GCaMP imaging may depict the neural foundation of functional connectivity networks detected in resting-state fMRI. neurovascular coupling | resting state | GCaMP | optical imaging | neural network activity F unctional magnetic resonance imaging (fMRI) measures local changes in deoxyhemoglobin concentration [HbR] as a surrogate for neural activity. In stimulus-evoked studies, the positive fMRI blood oxygen level-dependent (BOLD) signal corresponds to a decrease in [HbR] caused by a local increase in blood flow leading to over-oxygenation of the region. However, a growing number of studies are now using resting-state functional connectivity fMRI (fc-fMRI) in which spontaneous fluctuations in the BOLD signal are recorded in the absence of a task (1). Spatiotemporal correlations in these hemodynamic signals across the brain have been found to be bilaterally symmetric and synchronized in distant brain regions. This synchrony is interpreted as representing the connectivity of intrinsic neural networks (2-6). Many studies have identified changes in these resting-state networks during brain development (7,8) and in neurological and even psychological disorders (9-11). However, understandin...

Highlights d Neural inputs to Drosophila motion detector T5 are state and stimulus dependent d Their temporal responses are more biphasic in certain conditions d T5 responses can be explained by linear summation of state/ stimulus-dependent input d A biologically constrained model predicts T5 motion responses across conditions

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