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. Author manuscript; available in PMC: 2021 Feb 5.
Published in final edited form as: Neuron. 2019 Dec 3;105(3):549–561.e5. doi: 10.1016/j.neuron.2019.10.033

Figure 5. Evoked vascular reactivity and paravascular clearance rates are reduced during visual stimulation in 8–10 months old APP/PS1 mice.

Figure 5.

Evoked vascular reactivity upon visual stimulation is impaired in transgenic (Tg) mice compared to wild-type (WT) mice, as visualized by the averaged hemodynamic response functions (A; shaded areas represent standard deviations), and the quantification of the maximum amplitude of the power at 0.05 Hz after Fourier transform (B; 0.043 ± 0.034 1/Hz (n=22 vessels in 5 mice) in Tg vs. 0.13 ± 0.069 1/Hz (n=18 vessels in 9 mice) in WT mice, t-test, p<0.0001). Visual stimulation during the period of extravasated fluorescein dextran clearance resulted in slower clearance rates in Tg compared to WT mice (C), and can be explained by the significant difference in evoked vascular reactivity as quantified by the maximum amplitude (expressed as the power of the peak at 0.05 Hz) per vessel (D; 0.015 ± 0.012 1/Hz (n=13 vessels in 5 mice) in Tg vs. 0.027 ± 0.016 1/Hz (n=11 vessels in 7 mice) in WT mice, t-test, p=0.033). Quantification of the fluorescein dextran decay curves revealed significantly slower clearance rates during visual stimulation in Tg compared to WT mice, as expressed by area under the curve (AUC) (E; 1017 ± 433 in Tg vs. 638 ± 226 in WT, t-test, p=0.016). The maximum amplitude of the evoked vascular reactivity during clearance significantly correlated with AUC (F; Spearman’s ρ −0.59, p=0.0041). Note: two outliers were removed from the correlation to enable reliable curve fitting, but even without removing them the correlation remained significant (p=0.028). Error bars in C represent standard error of the mean. Median and range are indicated in B, D, and E. * p<0.05, ** p<0.01, *** p<0.001.