Figure 4.

(Top) Model prediction of the increase in the extra-vascular $P_{{\text{O}}_{\text{2}}}$ (C_t) necessary to represent the increase in medium artery $P_{{\text{O}}_{\text{2}}}$ (input, C_a) and small artery $P_{{\text{O}}_{\text{2}}}$ (output, C_v) considering the measured increase in CBF and a constant PS_c (Eq. 2, Figure 1). A higher extra-vascular $P_{{\text{O}}_{\text{2}}}$ level requires a smaller activation-evoked increase in extra-vascular $P_{{\text{O}}_{\text{2}}}$ to describe the data (i.e., small artery $P_{{\text{O}}_{\text{2}}}$). (Bottom) Model prediction of the decrease in PS_c (i.e., oxygen permeability) necessary to describe the increase in medium and small artery $P_{{\text{O}}_{\text{2}}}$ during increased neural activity while maintaining the extra-vascular $P_{{\text{O}}_{\text{2}}}$ level constant.