Hi Rik,
Both things are available in Fieldtrip which is included in SPM8.
On Wed, Nov 18, 2009 at 1:53 PM, Rik Henson
<[log in to unmask]> wrote:
>
> Do you know of any functions/toolboxes in
> SPM8 to:
>
> 1. Do a straight Fourier transform (ideally with tapers) for each channel
> across an epoch (ie, without using wavelets, ie if one does not want a time
> dimension)?
>
This can be done using the function freqanalysis (ft_freqanalysis from
SPM) with cfg.method = 'mtmfft' . If you do:
D = spm_eeg_load;
data = D.ftraw;
you'll get data in Fieldtrip format that you can use as an input to
that function. For other settings see the headers of freqanalysis and
freqanalysis_mtmfft that you can find in /external/fieldtrip/private.
Since in SPM there is little support for data without time dimension
(I'm not sure how well @meeg will handle a TF dataset with a single
time point, but you can try) if you want to generate scalp x frequency
images you might need to write your own code for that.
> 2. Calculate a Current Source Density for EEG - ie a topography of the
> spatial derivative of the potential?
>
This can be done with the function scalpcurrentdensity
(ft_scalpcurrentdensity). The same idea as above. You can then convert
the output back to SPM dataset using spm_eeg_ft2spm.
Best,
Vladimir
> R
>
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