Fig. 3

Effect of nicotine on olfactory bulb blood flow responses induced by olfactory nerve stimulation. Stimulus frequencies were 2 (a, d, g), 20 (b, e, h), and 100 Hz (c, f, i). a–f Sample recordings taken before (a–c) and after (d–f) the intravenous injection of nicotine (30 μg/kg). g–i Graph summarizing the time course of regional blood flow responses in the olfactory bulb ipsilateral to olfactory nerve stimulation averaged every 1 s, before (black line) and after (red line) nicotine injection. Changes in regional blood flow are expressed as percentages of the corresponding basal values (mean value for 10 s before time zero). Each point and vertical bar represent the mean ± SEM (n = 8). Data depict blood flow changes measured using laser Doppler (n = 4) or laser speckle (n = 4) flowmetry. Statistical comparisons of changes in regional blood flow in response to olfactory nerve stimulation before and after nicotine injection were conducted using two-way repeated-measures ANOVA (^#p < 0.05; ^##p < 0.01) followed by Bonferroni’s multiple comparison test (*p < 0.05; **p < 0.01)