[FieldTrip] surrogates for Phase lag index

[HINDRIKS, RIKKERT]

Constructing surrogate time-series for PLV is more straightforward since,
in this case, the nullhypothesis is the absence of phase-locking.
Surrogate pairs of time-series can be constructed for example by
phase-randomization in the Fourier domain.

Rikkert


On Wed, Jul 9, 2014 at 9:01 PM, Bastien Boutonnet <bastien.b1 at gmail.com>
wrote:

> I guess I will tag along to this discussion, in saying that I have been
> having the same burning question for a while.
>
> My issues have been along those lines: when I run some kinds of
> connectivity analyses (be it PLI, wPLI or PLV), how do I make sure the
> values I obtain are "legal" (or different from 0).
>
> B
>
> –
> Bastien Boutonnet, Ph. D.
> Postdoctoral Research Associate
> Department of Psychology
> University of Wisconsin, Madison
> bastienboutonnet.com
>
>
> On 9 July 2014 13:39, HINDRIKS, RIKKERT <rikkert.hindriks at upf.edu> wrote:
>
>> Hi Lidia,
>>
>> I have the same question and I don't think the answer is trivial: one
>> would have to construct pairs of surrogate time-series under the
>> nullhypothesis of zero phase-lag-index. With other words: construct pairs
>> of time-series who's instantaneous phases are coupled
>> to the same extent as the recorded time-series but with zero lag. In my
>> case, the question is how to test for a significant lag via the
>> cross-correlation function.
>>
>>
>> Kind regards,
>> Rikkert
>>
>>
>> On Wed, Jul 9, 2014 at 8:18 PM, Lidia Mijas <lid.mijas at gmail.com> wrote:
>>
>>> Hi all,
>>>
>>> I am wondering if fieldtrip has any options for computing surrogates?
>>> I am tryng to assess confidence level for my Phase Lag Index results (
>>> to determine whether it is significantly larger then 0)
>>>
>>> But maybe someone has a better idea how to do it?
>>> Not sure if it matters so just to mentioned that my PLI was computed at
>>> the source level on beamformed signals.
>>>
>>> Many thanks for any suggestion.
>>>
>>> Lidia
>>>
>>> _______________________________________________
>>> fieldtrip mailing list
>>> fieldtrip at donders.ru.nl
>>> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
>>>
>>
>>
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>
>
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