Hi Lluis,
If you did the epoching via the standard GUI then your stimulus
should be at time 0, which according to your description should be the
middle of the trial. If you want to know the corresponding index you
can do:
D = spm_eeg_load(filename);
D.indtime(0);
Vladimir
On Thu, Apr 22, 2010 at 8:02 PM, Lluis Fuentemilla
<[log in to unmask]> wrote:
> Hi Vladimir,
>
> I'm analysing some MEG/EEG data with SPM. Normal epoching and preprocessing.
>
> I epoched the data into a long 2sec window but my event of interest comes at
> second 1. Meaning then that I have -1000ms of baseline and 1000 of
> post-stimuli data. Data was originally collected at 460Hz and I downsampled
> to 300Hz after epoching. This means I have 660 timepoints. That's actually
> what I got from SPM.
>
> I'd like to know if I should then expect to have my stimuli onset at
> timepoint 330 (660/2)? Or SPM does some sort of recalculation of the epoched
> data that I could be misleading when transferring it to matlab.
>
> Many thanks for your help! Hope everything is ok in London.
>
> Best wishes,
>
> Lluís
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