Fig. 9.

Flow changes in deep capillaries from window and electrode implantation over 1 year. (a) Example flow map from electrode animal showing mapping range ($\mathrm{\Delta }f$ to $v$) from noise floor to saturation (0 to $2.0\mathrm{mm}/\mathrm{s}$). (b) Linear calibration curve for bandwidth to velocity mapping calculated from flow maps acquired with a diffuse uniform scattering phantom moving on a precision linear stage. (c) Example histogram maps where intensity corresponds to count in the linear flow velocity range over time. Each vertical line of the map represents a traditional histogram curve. Overlay in red shows the maximum count for each time point in the histogram map. (d) Example large ($800\times 800\mu \mathrm{m}$) ROIs for the window-only and electrode animals. Region over the electrode is masked in further analysis because spurious hyper-reflective signals can arise from electrode pads and other specular surfaces on the electrode. Electrode mask corresponds to entire migratory region over the experiment duration. Metrics collected from the flow maps include average flow velocity, flow velocity mode, and total flow count (see text for description of each). Total flow count is normalized to the total ROI count (excluding electrode mask). There is no statistical difference between the window-only animals and the electrode-implanted animals in average flow velocity (two-way ANOVA, $p=0.98$) or flow velocity mode ($p=0.83$), but the difference in total flow count is significant ($p<{10}^{-5}$). (e) Total flow count in annular ROIs near the electrode with increasing proximity from electrode tip show statistical differences between groups at all distances (two-way ANOVA; $<100\mu \mathrm{m}$, $p<{10}^{-14}$, 100 to $200\mu \mathrm{m}$, $p<{10}^{-15}$, 200 to $300\mu \mathrm{m}$, $p<{10}^{-12}$). $\text{Scale bar}=200\mu \mathrm{m}$ on all images. Shaded area for all figures indicates $\pm \mathrm{SEM}$.