Fig. 1

Spatiotemporal changes in regional cerebral blood flow following olfactory nerve stimulation in aged rats. a Schema showing the area of blood flow recorded using a laser speckle contrast imaging device. b–e Sample recordings of regional cerebral blood flow and mean arterial pressure in one aged rat. b, c Averaged signal over selected 1-s period. d Differential signal changes were obtained from b and c by subtracting the baseline signal from the subsequent image (b: − 1 to 0 s, c: 5–6 s). e Sample recordings of the mean arterial pressure and the regional cerebral blood flow responses to olfactory nerve stimulation ipsilateral and contralateral olfactory bulb, and the ipsilateral frontal cortex (the region of interest from which data were extracted are indicated by the grey circles in a). f Signal changes (as percentages) in the ipsilateral olfactory bulb blood flow and the mean arterial pressure in response to olfactory nerve stimulation, averaged every 1 s. Changes in each parameter were expressed as the percentages of the corresponding basal values (the mean of the values from the 10 s before time zero). Each point and vertical bar represents a mean ± SEM (n = 5). *p < 0.05, **p < 0.01: significantly different from the mean pre-stimulus basal value (− 1 to 0 s), determined with a Friedman’s test followed by Dunn’s multiple comparison test