Widefield calcium imaging has recently emerged as a powerful experimental technique to record coordinated large-scale brain activity. Because of the spatial and temporal resolution of these measurements , they present a unique opportunity to characterize spatiotemporally coherent structures that underlie neural activity across many regions of the brain. In this work, we leverage analytic techniques from fluid dynamics to develop a visualization framework that highlights features of flow across the cortex, mapping time-varying sources and wave fronts that may be correlated with behavioral events. First, we transform the time series of widefield calcium images into time-varying vector fields using optic flow. Next, we extract concise diagrams summarizing the dynamics, which we refer to as FLOW (flow lines in optical widefield imaging) portraits. These FLOW portraits provide an intuitive map of dynamic calcium activity, including sources, sinks, and traveling fronts in the data, using the finite-time Lyapunov exponent (FTLE) technique developed to analyze time-varying manifolds in unsteady fluids. Importantly, our approach captures coherent structures that are poorly represented by traditional modal decomposition techniques. We demonstrate the application of FLOW portraits on  two widefield calcium imaging datasets : activity of the developing mouse cortex during the first 8 postnatal days, and spontaneous cortical activity in an adult mouse.
Widefield calcium imaging has recently emerged as a powerful experimental technique to record coordinated large-scale brain activity. These measurements present a unique opportunity to characterize spatiotemporal coherent structures that underlie neural activity across many regions of the brain. In this work, we leverage analytic techniques from fluid dynamics to develop a visualization framework that highlights features of flow across the cortex, mapping wave fronts that may be correlated with behavioral events. First, we transform the time series of widefield calcium images into time-varying vector fields using optic flow. Next, we extract concise diagrams summarizing the dynamics, which we refer to as FLOW (flow lines in optical widefield imaging) portraits. These FLOW portraits provide an intuitive map of dynamic calcium activity, including regions of initiation and termination, as well as the direction and extent of activity spread. To extract these structures, we use the finite-time Lyapunov exponent (FTLE) technique developed to analyze time-varying manifolds in unsteady fluids. Importantly, our approach captures coherent structures that are poorly represented by traditional modal decomposition techniques. We demonstrate the application of FLOW portraits on three simple synthetic datasets and two widefield calcium imaging datasets , including cortical waves in the developing mouse and spontaneous cortical activity in an adult mouse.
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Because of the spatial and temporal resolution of these measurements , they
These measurements
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spatiotemporally
spatiotemporal
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time-varying sources and
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sources, sinks, and traveling fronts in the data, using
regions of initiation and termination, as well as the direction and extent of activity spread. To extract these structures, we use
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three simple synthetic datasets and
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: activity of
, including cortical waves in
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cortex during the first 8 postnatal days,