Dear Vladimir,
¡¡¡¡If disconnected source doesn't affect the model, and if family A and family C have the same detailed models except for the disconnected source. In this case, I think family A and family C will get similar performances. I indeed specified my models like that, however, family A was much better than family C. It was this that confused me much. How do you think about this question?
¡¡¡¡May you a happy weekend!
¡¡¡¡Haoran.
At 2011-07-15 20:22:14£¬"Vladimir Litvak" <[log in to unmask]> wrote:
>Dear Haoran,
>
>From your schemes it's not clear what is the difference between A and
>C or between B and D. Also it's not clear how the models within each
>family differed so one thing you need to make sure is that you did
>your comparisons correctly. However, assuming the result is valid I
>would definitely interpret it with your interpretation (2). Namely,
>there is no evidence for the necessity of the hidden source to explain
>the data. Disconnected hidden source does not affect the model so your
>model A could as well be without the hidden source at all (but you
>were right to include the source without connecting it).
>
>Vladimir
>
>
>
>2011/7/15 ·ÉÄñ <[log in to unmask]>:
>> Dear SPM's users,
>> ¡¡¡¡I got some results using dynamic causal modeling (DCM for ERP,MEG).
>> However, I was surprised at the results. I built four basic families of DCM
>> (see attachment DCM_Model.jpg), expected the best model would appear in
>> family B or D. To my surprise, family A turned out to be the best (see
>> attachment bms_family). Then I inferred:
>> ¡¡¡¡1. The hidden source might latently present several other subcortical
>> sources which might closely related to my experiment. Moreover, family A had
>> the least limitations of the connections between hidden source and other
>> non-hidden sources. Finally, it became the best family of the four.
>> ¡¡¡¡2. Family A was had much less connections relative to Family B and D, so
>> its model complexity was lower. Finally, it became the best family of the
>> four.
>> ¡¡¡¡Are the inferences above reasonable? Or what's the role of the hidden
>> source when it has no connections between other sources in DCM? Any of your
>> help will be greatly appreciated.
>> ¡¡¡¡Thank you!
>>
>> --
>> Haoran LI (MS)
>> Brain Imaging Lab,
>> Research Center for Learning Science,
>> Southeast University
>> 2 Si Pai Lou , Nanjing, 210096, P.R.China