single trial/channel phase angles

[Karl Doron]

Great! - thanks for the helpful information. Now I'm having trouble
recovering frequencies below 6Hz using the wltconvol method. My trial time
window is 3.5 seconds, so I am guessing this has to do with a minimum number
of time bins left from the partial artifact rejection.

Does anyone have any recommendations for setting a minimum trial length, and
where I might do this?  minoffset?

Thanks,
karl doron

On Wed, Mar 10, 2010 at 7:48 PM, Brian Roach <brian.roach at ncire.org> wrote:

>  Hi Karl,
>
> You can use wltconvol if you edit it.  If you step through the code, and
> find the spot where data are converted form complex numbers to power values,
> you only need to remove the abs(***) statement to keep the data in complex
> form.  This is how we've done it, but you may have a different version of
> the code:
>
> if keep == 1
>             powdum = (2.* abs(autspctrmacttap)  ./ data.fsample) .^ 2;
>         elseif keep == 2
>             %this is where we retain complex values:
>             powdum = (autspctrmacttap  ./ data.fsample);
>         end
>
>
> Hope this helps,
> Brian
>
>
>
> On 3/10/2010 10:28 AM, Karl Doron wrote:
>
> Hello Jan-Mathijs,
>
> I'm able to find the complex trial data now, but I've been avoiding the
> mtmconvol method because I don't have very good grasp on it. I'm getting
> phase angles greater than pi. Is there a simple way to run it on some
> simulated data?
>
> I'm trying to find a periodic signal at 2Hz with non-stationary gamma
> transients linked to its phase.
>
> Thanks for any feedback!
>
> -karl
>
> On Wed, Mar 10, 2010 at 3:32 PM, jan-mathijs schoffelen <
> jan.schoffelen at donders.ru.nl> wrote:
>
>> Hi Karl,
>>
>> freqanalysis with method = 'mtmconvol' allows you to keep the fourier
>> coefficients (cfg.output = 'fourier') so you'll get a complex representation
>> there.
>>
>> Best,
>>
>> Jan-Mathijs
>>
>>
>>
>> On Mar 10, 2010, at 2:36 PM, Karl Doron wrote:
>>
>>  Hello,
>>>
>>> I'm looking at some MEG data and have a hypothesis about cross frequency
>>> coupling. Specifically, a relationship between lower frequency phase and
>>> higher frequency amplitudes. I'm trying to save and view the phase angles
>>> after doing wavelet analysis using wltconvol.
>>>
>>> If this is implemented -great! Otherwise, it seems that somewhere after
>>> line
>>> 216 of ft_freqanalysis_wltconvol.m (after the ifft), I should be able to
>>> save the complex numbers and use angle(input) to find the phase angle of
>>> each time point on a trial by trial basis. It seems easier to do in the
>>> 'tfr' wavelet code, but the time domain covolution is very slow.
>>>
>>> Thanks for any help!
>>>
>>> Karl Doron
>>>
>>> ----------------------------------
>>> The aim of this list is to facilitate the discussion between users of the
>>> FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG
>>> and EEG analysis. See also
>>> http://listserv.surfnet.nl/archives/fieldtrip.html and
>>> http://www.ru.nl/neuroimaging/fieldtrip.
>>>
>>>
>>  Dr. J.M. (Jan-Mathijs) Schoffelen
>> Donders Institute for Brain, Cognition and Behaviour,
>> Centre for Cognitive Neuroimaging,
>> Radboud University Nijmegen, The Netherlands
>> J.Schoffelen at donders.ru.nl
>> Telephone: 0031-24-3668063
>>
>>
>> ----------------------------------
>> The aim of this list is to facilitate the discussion between users of the
>> FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG
>> and EEG analysis. See also
>> http://listserv.surfnet.nl/archives/fieldtrip.html and
>> http://www.ru.nl/neuroimaging/fieldtrip.
>>
>
> ----------------------------------
>
> The aim of this list is to facilitate the discussion between users of the
> FieldTrip toolbox, to share experiences and to discuss new ideas for MEG and
> EEG analysis.
>
> http://listserv.surfnet.nl/archives/fieldtrip.html
>
> http://www.ru.nl/fcdonders/fieldtrip/
>
>
>

----------------------------------
The aim of this list is to facilitate the discussion between users of the FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html and http://www.ru.nl/neuroimaging/fieldtrip.
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