Dear Saurabh,
The original implementation of DCM-IR expects data in the time domain.
TF computation is done by DCM code. I'm not sure what happens when you
re-convert your TF dataset but I doubt it's something that would lead
to a valid result. I once implemented a workaround to feed TF data
directly into DCM. It's been years since I last tested it so it might
not work any more because of more recent code changes. But that would
expect one trial per condition.
Best,
Vladimir
On Thu, Mar 1, 2018 at 6:32 AM, Saurabh Sonkusare
<[log in to unmask]> wrote:
> Hi SPM gurus,
>
> I am working with intracranial EEG data (stereo-EEG) and want to implement DCM for induced response (DCM-IR). I have 3 conditions in my paradigm and 3 electrode channels (ROIs). I have converted the data to spm format from EEGLAB format. I have also prepared the data by assigning the channels as 'LFP'. Further, I have computed the time-frequency (TF) spectrum and subsequently the rescaled TF. The resulting data in the 'D' struct file is 4-d with size 3 x 48 x 351 x 110 corresponding to channels x frequency x time points x trials. To use this file for DCM for induced response, I get an error-
>
> "The requested file is not ready for DCM use. Use prep to specify sensors and fiducials or LFP channels."
>
> However if I convert this rescaled TF file again to spm format the data is 3d corresponding to channels x time points x trials, I do not get an error and I can proceed with the imlementation of DCM-IR. I have also checked the test MEG data set for DCM for induced response. The data there is 3 d corresponding to channels x time points x trials. It was my understanding that DCM-IR takes in the TF or event related spectral perturbation (ERSP's) which would require both time and frequency information. Is this the correct way to implement DCM-IR?
>
> Also, if the error I am getting previously is about the sensors/ LFP channels, the 4D data should be fine I suppose. Can you clarify this?
>
> Appreciate your help regarding this.
>
>
> Regards,
> Saurabh
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