Dear Darren
Thank you for your response.
I understood very well.
Sincerely,
Shoichi
>Dear Shoichi
>
>> ================================
>I found previous my description was wrong.
>However, can I use the fully connected model (5 regions,
>DCM.a = [1 1 1 1 1; 1 1 1 1 1; 1 1 1 1 1; 1 1 1 1 1; 1 1 1 1 1],
>DCM.b = [1 1 1 1 1; 1 1 1 1 1; 1 1 1 1 1; 1 1 1 1 1; 1 1 1 1 1],
>DCM.c = [1 1 1 1 1]'), in which all the regions have direct inputs ( DCM.c
=
>[1 1 1 1 1]').
>> ================================
>
>Generally it is best to drive the network through only 1 (or a small subset
>of) regions. Providing input to every region turns the DCM into more of an
>SPM-type model. I believe this was a comment made in the Friston et al.,
DCM
>paper.
>
>> Is this mathematically correct?
> I'm not sure about mathematically per se, but it is likely that by
driving
>all regions you will end up with a model that is either difficult to
>estimate or has all influences attributed to the driving connections.
>
>
>> Instead, if I have a hypothesis, is it better to use another model such
>as:
>DCM.a = [1 1 1 1 1; 1 1 1 1 1; 1 1 1 1 1; 1 1 1 1 1; 1 1 1 1 1],
>DCM.b = [1 1 1 1 1; 1 1 1 1 1; 1 1 1 1 1; 1 1 1 1 1; 1 1 1 1 1],
>DCM.c = [1 1 0 0 0]'?
>
>Yes- as Klaas and others have commented it is always best to test specific
>hypotheses with DCM. If you have hypotheses about the architecture then
test
>those hypotheses. If you are unsure then it is reasonable to choose a
>driving region, and then use a fully connected model for the A and B
>matrices.
>
>Best regards,
>Darren
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