[Eeglablist] Cross Channel Coherence analysis

[Makoto Miyakoshi]

> Will the power of spectrum also be confounded with the number of trials?

Technically speaking yes, but it's less obvious in the actual data compared
with ITC. I don't have a formal explanation for this, but probably it is
related to the fact that single-trial phase distribution is more stochastic
than single-trial power variance.

Makoto

2014-05-15 20:10 GMT-07:00 张雪 <zhangxue at psych.ac.cn>:

>
> Thank Makoto very much.  You mentioned that the comparison of ITC will be
> confounded by the number of trials. Will the power of spectrum also be
> confounded with the number of trials?
>
> -----原始邮件-----
> *发件人:* "Makoto Miyakoshi" <mmiyakoshi at ucsd.edu>
> *发送时间:* 2014年5月13日 星期二
> *收件人:* "张雪" <zhangxue at psych.ac.cn>
> *抄送:* "EEGLAB List" <eeglablist at sccn.ucsd.edu>
> *主题:* Re: [Eeglablist] Cross Channel Coherence analysis
>
>
> Dear Xue,
>
> > I want to know whether could I just treat different channels as
> different trials in the newtimef.
>
> Yes. EEGLAB also has crosstimef() function which you want to check out
> (there is GUI menu for it too).
>
> > And another question is whether the ITC values of different conditions
> could be averaged all subtracted directly.
>
> A problem in comparing ITC measures across condition/subjects is that the
> signal to noise ratio depends on the number of trials. If you compare
> 30-trial average and 100-trial average, you'll see significant difference
> allover the plot because 'background' ITC SNR is very different and
> interestingly event-related phase modulation is left as nonsignificant! So
> I would suggest that for fair comparison you do something like subsampling
> to have the same number of trials across conditions for ITC (which people
> don't do very often though).
>
> Makoto
>
>
> 2014-05-09 8:10 GMT-07:00 张雪 <zhangxue at psych.ac.cn>:
>
>>
>>
>> Dear all
>>        I'm trying to do cross-channel coherence which is similar to the
>> inter-trial coherence. I want to know whether could I just treat different
>> channels as different trials in the newtimef. And another question is
>> whether the ITC values of different conditions could be averaged all
>> subtracted directly. Has there anybody ever done this through EEGlab before?
>> Thanks
>> Zhang Xue
>> Psychological institute,
>> Chinese Academy of Science
>>
>>
>>
>>
>>
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>
>
>
> --
> Makoto Miyakoshi
> Swartz Center for Computational Neuroscience
> Institute for Neural Computation, University of California San Diego
>
>
>
>
>
>


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