Dear Csaba,
Before my time, but to the best of my knowledge the other parameters were fixed to ensure the stability of the estimations. I assume you've read the NeuroImage paper - http://www.sciencedirect.com/science/article/pii/S1053811907006489 . You may wish to contact the corresponding author if you'd like more detail.
Best,
Peter
-----Original Message-----
From: SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]] On Behalf Of Csaba Aranyi
Sent: 03 December 2015 10:58
To: [log in to unmask]
Subject: [SPM] DCM - estimated hemodynamic parameters
Dear DCM users,
I have a rather technical question about the hemodynamic parameters that are used in the Balloon model of DCM. Even though there are five or six parameters in this model, only three of those (signal decay, transit time and intra-extravascular signal ratio) are estimated.
Does anyone know anything about the decision of not estimating the other parameters? Are their variability not significant enough to make it worth estimating them? (I noticed, that the prior covariance of these parameters are much lower than the ones that are estimated.)
Thank you for your answers and thoughts in advance.
Csaba Aranyi
|