Figure 1.

Schematic illustrating the procedure for computing the BOLD signal, given the time courses of MTT, CTH, and $v_{\max }$. In the first step, the deoxyhemoglobin concentration at the capillary end is computed. In the second step, the venous compartment volume is computed from $\text{MTT}\left(t\right)$. The BOLD signal is finally computed from the deoxyhemoglobin concentration and venous compartment volume. Abbreviations: CMRO₂, cerebral metabolic rate of oxygen; CTH, capillary transit time heterogeneity; MTT, mean transit time; OEF, oxygen extraction fraction; $\overline{P_{\mathrm{t}}}$, mean oxygen concentration in the tissue; S, oxygen saturation; $v_{\max }$, maximum metabolic rate of oxygen; please refer to Table 1 for other variables [Color figure can be viewed at http://wileyonlinelibrary.com]