Figure 4.

Displays the cerebral vascular reactivity (CVR) of different subcortical structures based on pretest positive CVR (+CVR) and negative CVR (−CVR) voxel masks. Negative CVR in the pretest was often reversed by exposure to high altitude. Few subjects demonstrated negative reactivity when only considering voxels with a significant z‐statistic (P < 0.05) in the pallidum, putamen, and thalamus limiting statistical power. In all other structures, negative CVR was recorded in all subjects. Statistical symbols if marked on –CVR pre are statistically different from both +CVR and −CVR post. Alternatively, if statistical symbol is marked on −CVR post the difference is compared to +CVR. *P < 0.05; **P < 0.01; ^† P < 0.001.