Figure 5.

Relative CO activity in blobs and interblobs and across the cortical layers and its correlation to vascular density. Data from Weber et al. (2008) are added. The CO staining intensity was measured as gray values in black-and-white images from vertical sections (as in Fig. 1B) and tangential sections (as in Fig. 2A). CO activity was normalized as described in Materials and Methods to allow comparison of images from different section orientations, different overall staining intensities, and therefore different image acquisition parameters. The asterisks indicate a statistically significant difference, and the error bars show SEM. A, The histogram shows CO activity in arbitrary units for blobs and interblobs in horizontal and tangential sections from squirrel and macaque monkeys. It is significantly higher in blobs than in interblobs in both species investigated, which is already clearly visible by eye in Figures 1A and 2A. The differences are comparable across all acquisition modalities. In horizontal sections, it is 7.9% in Saimiri and 9.5% in Macaca, and in tangential sections, 12.0% in Saimiri and 9.9% in Macaca. B, The solid traces show the relative CO activity (bottom axis) across all cortical layers of the primary visual cortex in squirrel and macaque monkey. The course of the traces could already be assumed after the visual examination of Figure 1B. It also mirrors the capillary density shown in the dashed trace [top axis; only data for the macaque available from the study by Weber et al. (2008)]. C, Correlation between CO activity and vascular density across cortical layers, emphasizing the close relationship between CO activity and vascular length density (filled circles) and the good agreement with previously published data (open circles) (Weber et al., 2008). The data from blob and interblob areas on tangential sections (open squares and diamonds; x and y error bars show SD) also lie well within the same range.