Hello,
I am conducting a DCM analysis and I am having a problem running
models where the modulatory variable (reward level) acts on the self
connections. I have a 3 region model, and I want to test a set of
models where all 3 regions' self-connections can be modulated by
reward level. To do this, I set the values of the DCM.b diagonal
entries to 1. However, when I estimate the models, the DCM.B values
on the diagonal are 0. In fact, the DCM.B matrix is identical for
models with and without the modulated self-connections.
EG. DCM.B is identical for DCM.b matrices A and B where
A=[ 1 0 1 and B = [0 0 1
0 1 1 0 0 1
0 0 1] 0 0 0]
I know that it is possible to specify self-connections as being
modulated by reward (see Lee, Friston, and Horwitz 2006) so I don't
understand what is happening. If it helps, my DCM.A values on the
diagonal are -1 for all models. Any help would be appreciated.
Thank you,
Ian
|