[FieldTrip] Changing dimord of Cross Spectral Density matrix

Helen Wieffering helen.wieffering at gmail.com
Thu Oct 29 00:30:05 CET 2015


Hello again,

I've just realized the question in my previous e-mail is irrelevant when I
proceed with ft_connectivityanalysis instead, using 'granger' as the
method. I wasn't aware that this function could also perform nonparametric
granger methods.

Still, if anyone has insight on this or would like to connect about
approaches, I'd love to hear.

Best,
Helen

On Wed, Oct 28, 2015 at 6:37 PM, Helen Wieffering <
helen.wieffering at gmail.com> wrote:

> Dear Fieldtrip Users,
>
> I am trying to use the function ft_connectivitiy_csd2transfer in order to
> compute non-parametric Granger Causality measures.
>
> In order to do so, I have my frequency analysis data in the following
> form:
> freq =
>
>         label: {129x1 cell}
>        dimord: 'chan_freq_time'
>          freq: [4 4.5000 5 5.5000 6]
>          time: [1x41 double]
>     powspctrm: [129x5x41 double]
>      labelcmb: {8256x2 cell}
>     crsspctrm: [8256x5x41 double]
>           cfg: [1x1 struct]
>
> In my data, the crsspctrm matrix has a dimord of chan_freq_time --
> however, the function ft_connectivity_csd2transfer requires a dimord of
> chan_chan_freq(_time).
>
> Does anyone have insight on how to change the dimord of my data?
>
> I understand that Fieldtrip's ft_freqanalysis function treats (a, b) and
> (b, a) cross spectra as identical and therefore omits half of all possible
> combinations. Ideally, though, I'd like for my crsspctrm matrix to contain
> all possible combinations between channels, including the auto-spectra.
>
> Thanks for your help!
>
> Helen Wieffering
> Bowdoin College
>
>
>
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