Fig. 2. Baseline haemodynamics in HC and V1.

Estimated CMRO₂ a, CBF b and oxygen saturation (SO₂) c in HC (purple) and V1 (orange) in stationary mice in the dark (HC: 9 animals across 21 sessions; V1: 9 animals across 19 sessions, 1–5 sessions per mouse; data points are averages for each animal). d FITC-gelatin filled vessels (green) from the HC and neocortex of one NG2-DsRed mouse (pericytes are red). Scale bars represent 100 μm. Example images are projections of the 200 μm Z-stacks compared in e. e Capillary density in these slices was significantly lower in HC (N  =  6 slices, five mice) compared with V1 (N  =  5 slices, four mice). f Single capillaries were imaged in vivo using two-photon microscopy (HC: 55 vessels from 11 mice, V1: 54 vessels from 14 mice), and the average diameter of the vessels scanned did not differ between HC (mean: 4.9 µm) and V1 (mean: 5.2 µm, t test p  =  0.13). g Example line scan trajectory from one in vivo two-photon recording to represent the 99 vessels scanned in f (top; as input into the acquisition software—the actual trajectory will differ from that shown owing to mirror inertia). The scan path of the laser goes along (blue) and across (red) the capillary (labelled with i.v. Texas Red dextran, white. Dark stripes are RBCs). Each row in the corresponding line scan image (bottom) represents a single time point. As RBCs move, their shadow shifts along the vessel, so the angle of the stripes (left, under blue line) shows how fast they are moving. The vessel diameter can be measured from the intensity profile of the Texas Red-labelled lumen (right, under red line). The number of red blood cells per second can be calculated by counting the number of dark stripes (marked with yellow circles) within this time period. The vertical scale bar represents 5 ms, and the horizontal scale bar 5 μm. Despite the same vessel types being scanned in f, the average resting h haematocrit, i RBC flux and j RBC velocity were different between regions (statistical comparisons were made on individual vessels, N specified in f). Data in bar charts represent mean ± SEM, dots are individual vessels or mice, as indicated. P values are from independent sample t tests, or Mann–Whitney U tests (see Statistics Report Table SR1). Source data are provided as a Source Data file.