[FieldTrip] Circular Correlation coefficient

[David Syloni]

Dear Julian,

Thank you for the answer. I will try to apply it as you described.
However, it's important to note, that my data doesn't contain real trials,
this is a EEG during one continuous stimulus (110 sec).
Can your approach work also for   this case?


Thanks,


David

On Tue, Feb 2, 2016 at 1:51 PM, Julian Keil <julian.keil at gmail.com> wrote:

> Dear David,
>
> I won't discuss whether this is a sensible comment by the reviewer, but
> here are some basic steps that you could take.
>
> To compute the circular correlation between two signals, you obviously
> need to obtain the phase angles first.
> One option to do this is to use a Hilbert transform on band-pass filtered
> data (on a single-trial level)
> As soon as you have your single trial phase angles, you can compute the
> correlation between two signals within each subject.
> Once you have done this, you could see whether there is a consistent
> pattern over subjects.
>
> You can find similar approaches in the following papers:
>
> van Elswijk, G., Maij, F., Schoffelen, J.-M., Overeem, S., Stegeman, D.
> F., & Fries, P. (2010). Corticospinal Beta-Band Synchronization Entails
> Rhythmic Gain Modulation. Journal of Neuroscience, 30(12), 4481–4488.
> http://doi.org/10.1523/JNEUROSCI.2794-09.2010
>
> Keil, J., Timm, J., SanMiguel, I., Schulz, H., Obleser, J., &
> Schonwiesner, M. (2014). Cortical brain states and corticospinal
> synchronization influence TMS-evoked motor potentials. Journal of
> Neurophysiology, 111(3), 513–519. http://doi.org/10.1152/jn.00387.2013
>
> Good luck,
>
> Julian
>
> Am 02.02.2016 um 09:14 schrieb David Syloni:
>
> Dear Julian,
>
> Thank you for the answer. I was asked by reviewers to calculate  circular
> correlation instead of PLV.  Sorry for too general description.
> Actually, I found  the toolbox , but I don't understand how to compute
> " sample of angles in radians" (the input for the circ_corrcc function ).
> I would very appreciate a help to transform my fieldtrip data to the input
> format , required by circ_corrcc.
>
> Thanks!
>
>
> David
>
> On Tue, Feb 2, 2016 at 9:57 AM, Julian Keil <julian.keil at gmail.com> wrote:
>
>> Hi David,
>>
>> to compute circular statistics (e.g. phase correlations) you need to
>> leave fieldtrip a bit.
>> Here's the toolbox I usually use:
>> http://www.mathworks.com/matlabcentral/fileexchange/10676-circular-statistics-toolbox--directional-statistics-
>>
>> As you don't describe why you need circular statistics, it's a bit hard
>> to give a more helpful answer.
>>
>> Good luck,
>>
>> Julian
>>
>> Am 01.02.2016 um 13:40 schrieb David Syloni:
>>
>> > Dear Fieldtripers,
>> >
>> > I'm trying to apply connectivity analysis with  continuous EEG data.
>> >
>> > I'm using:
>> >
>> >
>> >
>> > cfg           = [];
>> > cfg.method    = 'mtmfft';
>> > cfg.taper     = 'dpss';
>> > cfg.output    = 'fourier';
>> > cfg.tapsmofrq = 4;
>> > cfg.width=2;
>> > cfg.foilim     = [0 250];
>> > cfg.keeptrials = 'yes';
>> > freq          = ft_freqanalysis(cfg, data_no_artifacts);
>> >
>> >
>> >
>> >
>> > cfg           = [];
>> > cfg.method    = 'plv';
>> > 'mtmfft'
>> > cfg.foilim     = [8 12];
>> > cfg.bandwidth=5;
>> > cfg.tapsmofrq  = 4;
>> > cfg.keeptrials = 'yes';
>> > cfg.output    = 'powandcsd';
>> > cfg.channelcmb       = c;
>> > coh           = ft_connectivityanalysis(cfg, freq);
>> >
>> > Right now I should calculate Circular Correlation  and I'm stuck with
>> it.
>> >
>> > I would very appreciate your help!
>> >
>> > Thanks in advance,
>> >
>> > David
>> > _______________________________________________
>> > fieldtrip mailing list
>> > fieldtrip at donders.ru.nl
>> > http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
>>
>>
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