Table 1.

Systemic input variable ranges for simulations. Step inputs in Fig. 3 are from the baseline to the upper bound of each range.

Input	Description	Units	Baseline	Lower	Upper
Pa	Mean arterial pressure	mmHg	100	75	125
${\mathit{P}}_{\mathit{a}}{\mathit{CO}}_2$	Partial pressure of ${\mathrm{CO}}_2$	mmHg	40	37.5	42.5
${\mathit{S}}_{\mathit{a}}{\mathit{O}}_2$	Arterial oxygen saturation	%	96	90	100⁎
u	Demand	–	1.0	0.75	1.25
Fluxy	Normalised LD flux	–	1.0	0.75	1.25

^⁎Spontaneous increase in arterial saturation was deemed implausible in typical functional activation experiments, so the baseline value of 96% was used as the upper bound when optimising this parameter for the scenarios in Fig. 5.