Fig. 1

Olfactory bulb blood flow responses following olfactory nerve stimulation. The effects of various intensities (a, b) and frequencies (c–e) of electrical stimulation of the unilateral olfactory nerve on regional blood flow in the olfactory bulb ipsilateral to the stimulus. a, b Stimulus frequency, 20 Hz. c–e Stimulus intensity, 300 μA. a, c Sample recordings of regional blood flow in the olfactory bulb. b, d, e Summarized responses of regional blood flow in the olfactory bulb measured at the maximal level within 8 s (1st peak) or later (2nd peak) after the onset of stimulation, and expressed as the percentage increase from the pre-stimulus basal blood flow (mean value of the 10-s duration). Each column and vertical bar represents the mean ± SEM (n = 6). The data depict blood flow changes measured by laser Doppler (n = 4) or laser speckle (n = 2) flowmetry. *p < 0.05, **p < 0.01: significantly different from the responses at an intensity of 20 μA (b) or frequency of 0.5 Hz (d), using one-way repeated-measures ANOVA followed by Dunnett’s multiple comparison test