[Eeglablist] Induced power from wavelet

[Makoto Miyakoshi]

Dear Nancy,

> And Matt, I agree that EEGLAB is performing the time frequency transform
prior to trial averaging. However, it is my understanding that this gives
us the total power, including both phase-locked (evoked) and non-phase
locked (induced) activity combined together. I was wondering how to
specifically get the values for the induced activity, which it seems would
involve a subtraction of total power minus evoked power.

Something like ERSP after ERP subtracted data to compute specifically
non-phase-locked oscillatory power? You probably need to do this ERP
subtraction manually then apply newtimef().

We don't do this ERP subtraction by default, except for SIFT.

Makoto



On Wed, Jan 25, 2017 at 6:56 PM, Lundin, Nancy B. <nlundin at indiana.edu>
wrote:

> Hello Makoto and Matt,
>
>
> Makoto, actually my question was related specifically to calculating
> induced/non-phase locked activity rather than dealing with ERSP in general.
>
>
> And Matt, I agree that EEGLAB is performing the time frequency transform
> prior to trial averaging. However, it is my understanding that this gives
> us the total power, including both phase-locked (evoked) and non-phase
> locked (induced) activity combined together. I was wondering how to
> specifically get the values for the induced activity, which it seems would
> involve a subtraction of total power minus evoked power.
>
>
> One suggestion I have received is to subtract the average ERP in the time
> domain from the data of each individual trial in the time domain, and then
> run a wavelet decomposition on this data to get the induced activity. I
> will try this unless anyone has any other suggestions.
>
>
> Thank you for your time,
>
> Nancy
>
>
> *Nancy Lundin*
> *Doctoral Student, Clinical Psychology & Neuroscience*
> Indiana University Bloomington
> Department of Psychological & Brain Sciences
> 1101 East 10th St.
> Bloomington, IN 47405
> ------------------------------
> *From:* matt schalles <matt.schalles at gmail.com>
> *Sent:* Wednesday, January 25, 2017 8:45 PM
> *To:* mmiyakoshi at ucsd.edu
> *Cc:* Lundin, Nancy B.; eeglablist at sccn.ucsd.edu
> *Subject:* Re: [Eeglablist] Induced power from wavelet
>
> Hi Nancy, et al.
>
> It is my understanding that the way EEGlab calculates ERSPs, the
> time-frequency transform is done prior to temporal averaging of trials,
> which should give you the induced activity, without having to do additional
> subtractions.
>
> cheers,
>
> Matt Schalles, Ph.D.
> Cognitive Neuroscientist, VA Health System
> Visiting Assistant Professor, Mills College
>
> On Tue, Jan 24, 2017 at 6:00 PM, Makoto Miyakoshi <mmiyakoshi at ucsd.edu>
> wrote:
>
>> Dear Nancy,
>>
>> I don't quite understand the question, but I guess that you want to know
>> how you deal with ERSP most straightforwardly? I think you use newtimef()
>> function, and visualize the first output as
>>
>> figure
>> imagesc(output); axis xy
>>
>> The basic figure is this. Then you change xaxis labels, yaxis labels,
>> etc. Do not forget to use eegh(); you perform an operation from GUI first,
>> then type eegh() to obtain the code executed.
>>
>> Makoto
>>
>> On Sun, Jan 22, 2017 at 3:01 PM, Lundin, Nancy B. <nlundin at indiana.edu>
>> wrote:
>>
>>> ​Hello list,
>>>
>>>
>>> I would like to calculate the induced ERSP in my data. I planned to run
>>> the wavelet decomposition on my data to calculate total power, and then
>>> separately run a wavelet over the averaged data to get the evoked activity,
>>> and then subtract the evoked from the total to get induced activity.
>>> However, when I manually average the trials, I get an error message when
>>> attempting to save my EEG datasets saying that the number of epochs in the
>>> data structure is not the same as the number of epochs in the data (which
>>> makes sense, since I averaged).
>>>
>>>
>>> I was wondering if there was a more direct way to calculate induced ERSP
>>> in EEGLAB rather than this manual subtraction method?
>>>
>>>
>>> Thank you,
>>>
>>> Nancy
>>>
>>>
>>> *Nancy Lundin*
>>> *Doctoral Student, Clinical Psychology & Neuroscience*
>>> Indiana University Bloomington
>>> Department of Psychological & Brain Sciences
>>> 1101 East 10th St.
>>> Bloomington, IN 47405
>>>
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>>
>>
>>
>> --
>> Makoto Miyakoshi
>> Swartz Center for Computational Neuroscience
>> Institute for Neural Computation, University of California San Diego
>>
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>
>


-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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