Table 3. State variables.
A total of fourteen independent states are fit to each data set in this model. The dynamic changes in arteriole dilation and CMRO2 are modeled by several amplitude and timing parameters, which describe the temporal basis functions used in the model (described in the text). In addition, several static parameters describing components of the model are also fit. In the joint-fitting of multiple conditions, these static variables are estimated globally across all conditions, while independent estimates are obtained for each of the dynamic variables. Physiological ranges were used to bound the estimates of each of these parameters. *Oxygen saturations were estimated as a change from the previous compartment to avoid discontinuities in the model fitting routine.
| Symbol | Description | Physiological Range | Citation | ||
|---|---|---|---|---|---|
| Dynamic | Arteriole dilation temporal basis | ΔRA | Change arterial resistance | [0-10] % | -- |
| τpeak | Time to maximum resistance change | [0-6] s | -- | ||
| σA | Width of temporal resistance change | [0-6] s | -- | ||
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| CMRO2 temporal basis | ΔCMRO2 | Relative change CMRO2 | [0-10] % | -- | |
| τonset | Time to onset of CMRO2 change | [0-6] s | -- | ||
| σc | Width of temporal CMRO2 change | [0-6] s | -- | ||
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| Structural | RA(0) | Initial arterial resistance | [0.20-0.90] AU | (Mandeville et al 1998b; Boas et al 2003 | |
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| Windkessel parameters | β | Windkessel vascular reserve | [1-5] AU | (Mandeville et al 1998b; Boas et al 2003; Zheng et al 2005) | |
| τ | Vascular transit time | [0.5-4] s | (Mandeville et al 1998b; Zheng et al 2002; Boas et al 2003) | ||
| τpial | Pial venous transit time | [0-4] s | -- | ||
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| [HbT]o | Total baseline blood volume | [40-140] uM | (Zheng et al 2005; Boas et al 2003) | ||
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| SaO2 | Baseline arteriole saturation | [95-100] % | (Herman et al 2006) | ||
| ScO2 | Baseline capillary saturation | [60-90] % * | |||
| SvO2 | Baseline venial saturation | [55-89] % * | |||