Total cerebral blood volume changes drive macroscopic cerebrospinal fluid flux in humans
Fig 2
Bidirectional grey-matter CBF changes induced by a hypercapnic challenge.
(a) Schematic depiction of the experimental design: a gas mixture of CO2 and medical air was applied over a medical mask in awake subjects (top). Schematic time course of the inspiratory CO2 concentrations of the applied gas mixture, including two 180 s segments with elevated CO2 levels (5% vol/vol). Transition periods lasted ~ 30 s due to the ramp time of the gas mixer. (b) Example scan positioning for the pCASL imaging volume (red) and labeling plane (yellow) in a representative subject superimposed on a sagittal T1 image (left) and a sagittal reconstruction of a 3D-phase contrast angiogram (right). (c) Whole brain cerebral blood flow (CBF) maps (top) and extracted subject-average (n = 17) time course of gGM CBF (bottom). Mean (black) ± SEM (grey). CO2 application periods are color-coded in purple. (d) Subject-average maps of CBF changes for transitions from normocapnia to hypercapnia (N → H, left) or from hypercapnia to normocapnia (H → N, right). (e) Global grey matter ∆CBF values for N → H (n = 34, left) or H → N (n = 34, right) transitions (2 for each subject). One-sample t test (individual groups). ***p < 0.001. Source data for Fig 2e are available in the source data file (S1 Data).