Fig. 2.

SPM-OCM protocol: An angiogram (a) is first acquired on the area of response previously localised using OIS imaging. At a selected lateral position (highlighted by the yellow dashed line in a), an acquisition of total blood flow during the electrical stimulation is performed (b). Subsequently, an angiogram is acquired at the same location for segmentation purposes (c). The vessels in the selected angiogram are segmented manually via a MATLAB interface (d) and the total blood flow timetraces of each individual segmented vessel are isolated and smoothed temporally. Finally, a GLM analysis, using a design matrix (example for the short stimulation paradigm shown in (f)), is performed on each timetrace and leads to a p-value map, displaying the vessel’s reactivity (e). The design matrix used in the GLM analyses comprised the velocity response regressor h, its derivative dh/dt, a baseline flow value CBFv0 and a drift component (f). An illustration of the results obtained by the GLM analysis is displayed in tile (g), showing that the p-value obtained by the regression is sensitive to the noise in the data, pointed by the arrows. Scalebars: 100 µm.