[FieldTrip] FT_CONNECTIVITY_WPLI

[McGowin, Inna]

Thanks Nathan!
Sorry I am not a frequent FieldTrip user and not sure how a data
stutructure should look like after ft_preprocessing.

I have two time-series for two virtual electrodes; the time-series were
calculated by CTF SAM (synthetic aperture magnetometry), and then extracted
and converted into a text file (and Excel if needed).

Now I want to use the weighted Phase Lag Index (wPLI) and compare these two
time-series for any coupling. My understanding is that the input for this
function should be a cross-spertal density matrix?

I tried to follow the steps you suggested with the CTF dataset that
includes both the original data and the two time-series but got stuck on
ft-freqanalysis as it requires lots of inputs I am not knowledgeable about,
plus it still works with the whole dataset instead of just two time-series
that I am interested in.

Is there a short-cut for CTF SAM output dataset?

Thanks!
Inna



On Thu, Mar 14, 2013 at 4:22 PM, Nathan Weisz <nathanweisz at mac.com> wrote:

> Hi inna,
>
> never used this method, but repetitions means you need single trials (it's
> not an averaged time-series you are talking about, right?).
>
> here some suggestions:
>
>    - when importing your data from Excel (how did that happen? :-)) into
>    matlab, make a data structure that looks like one following
>    ft_preprocessing.
>    - then run ft_freqanalysis with output "powandcsd" and keeptrials
>    "yes" as options (and other options of course). this is at least what i
>    assume after looking ft_connectivityanalysis
>    - then enter the structure which results from your former step into
>    ft_connectivityanalysis with method specified as "wpli_debiased"
>
> perhaps wpli-experts want to correct me if i got something wrong.
>
> good luck,
> n
>
>
>
>
> On 14.03.2013, at 20:41, McGowin, Inna wrote:
>
> Hello fieldtrippers!
>
> I would like to calculate wPLI (weighted phase lag index) for two
> time-series (created by a beamformer).
> It's described here:
> http://fieldtrip.fcdonders.nl/reference/ft_connectivity_wpli
> What do *repetitions *mean in input argument for the function?
>
> I have the data in a text or Excel format that I could import into Matlab
> directly:
> 1st column is time,
> 2nd column is 1st source intensities and
> 3rd column is 2nd source intensities.
>
> Assuming I get my input data in the correct format, is this a correct line
> to call the function (I need a debiased wPLI)?
>
> [wpi, v, n] = ft_connectivity_wpli(input, debias 1)
>
> Thanks,
>
> Inna
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-- 
Inna McGowin
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