About scalp x frequency images - it might be very easy to generate
those if you just 'fool' SPM into thinking that frequency is time.
Vladimir.
On Wed, Nov 18, 2009 at 2:38 PM, Vladimir Litvak
<[log in to unmask]> wrote:
> 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
>>
>>
>> --
>>
>> -------------------------------------------------------
>> Dr Richard Henson
>> MRC Cognition & Brain Sciences Unit
>> 15 Chaucer Road
>> Cambridge
>> CB2 7EF, UK
>>
>> Office: +44 (0)1223 355 294 x522
>> Mob: +44 (0)794 1377 345
>> Fax: +44 (0)1223 359 062
>>
>> http://www.mrc-cbu.cam.ac.uk/people/rik.henson/personal
>> -------------------------------------------------------
>>
>>
>>
>
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