Hi Klaas,
Thanks for your reply. When I set up the model, I choose one region as a
driving input (after entering the extrinsic conditions). I tried a model
that is very similar to the attention model from your group where I entered
one condition and one region (like photic condition and V1) and then other
conditions and connections. The model stopped after the first iteration. I
might be missing something here. So any leads are appreciated!
Thanks
Elif
On Fri, 1 Jul 2005 09:35:27 +0100, Klaas Enno Stephan
<[log in to unmask]> wrote:
>At 19:54 30/06/2005, Elif Ozdemir wrote:
>>On Thu, 30 Jun 2005 13:45:14 +0100, Christian Matthiae
>><[log in to unmask]> wrote:
>>
>> >Hi Elif,
>> >i am not an expert, so i am not completely sure about this.
>> >But i think there is no problem, as you dont get an error, but only a
>> >warning. Every DCM matrix contains not specified connections, which can
not
>> >be estimated. During estimation these connections get the value Nan,
which
>> >is indicated by the displayed warning. So i think your estimation was
>> >finished correctly. The reason that you get this warning after the first
>> >step is, that iteration stops, if the changes from one step to the next
are
>> >smaller than a threshold (1e-6 i think). This condition is met in your
>> >analysis after the first step (dp: 1.139079e-21). This is a little
>> >astonishing for me, but perhaps could be due to a very simple model?
>> >If i am wrong here one of the spm/dcm should please correct me.
>> >Hope this helps,
>> >Christian
>> >
>> >
>> >On Thu, 30 Jun 2005 01:26:49 +0100, Elif Ozdemir <[log in to unmask]
>> >HARVARD.EDU> wrote:
>> >
>> >>Dear all,
>> >>
>> >>I am conducting a DCM analysis on a dataset that we acquired from a
>>subject
>> >>using a sparse temporal sampling method (TR=15, TA=1.75 sc). I have
>>defined
>> >>three VOIs for two (out of four) conditions. When I do the estimation,
I
>> >>get the error message below after the first iteration. I have read the
>> >>previous posts about this error and have the latest DCM updates.
>> >>
>> >>After getting the error message, I am still able review the results.
The
>> >>histogram is drawn only for B probabilities, not for B modulatory
effects.
>> >>In addition, even though the VOIs are circled, there are no numbers.
>> >>
>> >>I have replicated the results of the attention data from Dr.Penny's
>>website
>> >>without these error messages.
>> >>
>> >>Any ideas how to fix this? Any input/help is greatly appreciated!
>> >>Thanks!
>> >>
>> >>Elif
>> >>
>> >>"E-Step(-): 1 F: -1.043264e+03 dp: 1.139079e-21
>> >>Warning: Returning NaN for out of range arguments
>> >>> In /usr/local/spm2/spm_Ncdf.m at line 76
>> >> In /usr/local/spm2/spm_dcm_estimate.m at line 72
>> >> In /usr/local/spm2/spm_dcm_ui.m at line 312"
>>
>>Hi Christian,
>>
>>Thanks for the message. I have specified several DCMs with conditions
>>ranging from two to 6, VOIs from 2 to 6 and intrinsic conditions from 2 to
>>12. None of them worked (at least completely). A and B probabilities are
>>there. But no numbers on the regions. There are dashed lines instead of
>>solid ones with red dots around the VOIs.
>>
>>In the last DCM model, I had 8 conditions in the design matrix, took two
of
>>those conditions to the DCM, had 6 VOIs and 12 intrinsic connections. For
>>the condition one and two, I had same number of connections (I think 6).
>>The NaN error message still comes up after the first iteration.
>>
>>Any ideas as to how I could make these dashed lines solid and see the
>>corresponding numbers? Loading DCM.A mat gives me only -1s and 0s.
>>
>>Any help is very much appreciated!!!
>>
>>Elif
>
>
>
>Dear Elif,
>
>is it possible that you forgot to specify driving inputs for your
>model? Without such driving inputs, there will be no dynamics
>whatsoever, and the model will converge at the first iteration.
>
>Best wishes
>Klaas
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