Fig. 3

Changes in the baseline fluorescence intensity in each region at each depth. Each symbol indicates data obtained from the single ellipsoid region shown in Fig. 2A. The baseline fluorescence intensity was defined as a mean value of the averaged wave from − 1.5 to − 5.0 s triggered by the C4 inspiratory burst at each focal depth (see the Materials and Methods section). Ordinate: the percentage of the baseline fluorescence intensity at each focal depth to the baseline fluorescence intensity at a depth of 0 μm. Abscissa: the focal depth. Data from the strong (n = 15), open circles; weak (n = 10), open triangles; and no (n = 13), filled circles inspiratory-modulated groups are shown. In all regions, the baseline fluorescence intensity gradually decreased with increasing focal depth