Figure 2.
(a) Speckle contrast image of mouse cortex taken though a cranial window. A maximum intensity projection of a multiphoton fluorescence image stack (b) of the area highlighted by the blue square in (a) indicates that even in areas of the speckle contrast images that contain no obvious surface vasculature, the speckle contrast values contain contributions from subsurface microvasculature. The relative amounts of this subsurface contribution will vary depending on tissue type and surface preparation. Note that only the right portion of the surface vessel that is visible in the speckle image (a) is observed in the multiphoton fluorescence image stack since the image stack began at a depth slightly below the left hand portion of the vessel. The image in (c) shows a color coded map of τc values from a mouse cortex where a threshold has been applied to highlight flow within different vascular compartments.