[Eeglablist] Alpha power spectrum assymetry

Thu Oct 11 20:59:46 PDT 2012

Dear Meltem,

I'm wondering if this questions was answered or solved. It seems just
calculating the channel spectra solves the problem. Would you tell me
what did not work in detail?

Makoto

2012/10/2 Meltem Ballan <meltball at rocketmail.com>:
> I have a related question. I am extraction frequency bins of 3-5 Hz, 6-9 Hz
> and 10-13 Hz (using FIR). I would like to extract the band power and mean
> band power for selected channels (I have already selected the channels using
> select data option). So, basically I would like to extract all selected
> channel powers (33 in my case) and mean band powers. I tried to use
> spectopo(); however, it gives parsing error.
> My understanding is that in order to use pwelch and spec I need to extract
> the preprocessed data in .mat format. Is there any other way to calculate
> channel powers and mean powers ?
> Thanks in advance
> Meltem
>
> ________________________________
> From: Simon-Shlomo Poil <simonshlomo.poil at cncr.vu.nl>
> To: "Achim, André" <achim.andre at uqam.ca>
> Cc: "eeglablist at sccn.ucsd.edu" <eeglablist at sccn.ucsd.edu>; "Poil, S.S."
> <s.s.poil at vu.nl>
> Sent: Monday, June 20, 2011 4:42 PM
> Subject: Re: [Eeglablist] Alpha power spectrum assymetry
>
> ups. yes. that's true..
>
> I would btw. also recommend to use 'pwelch' or 'spec' directly.
>
> -Simon
>
> 2011/6/20 Achim, André <achim.andre at uqam.ca>:
>> The code below "spectra(1, find(freqs >= 8 | freqs <=13))" uses | (or)
>> instead of & (and), which would return all available frequencies. Besides,
>> the "find" is not necessary; it would be more efficient to write:
>> "spectra(1, freqs >= 8 & freqs <=13)"
>>
>> André Achim
>>
>> -----Message d'origine-----
>> De : eeglablist-bounces at sccn.ucsd.edu
>> [mailto:eeglablist-bounces at sccn.ucsd.edu] De la part de Simon-Shlomo Poil
>> Envoyé : 19 juin 2011 16:12
>> À : nikos dhmou; eeglablist at sccn.ucsd.edu
>> Objet : Re: [Eeglablist] Alpha power spectrum assymetry
>>
>> Hi Nikos,
>>
>> The output of spectopo is
>>  Outputs:
>> %        spectra  = (nchans,nfreqs) power spectra (mean power over
>> epochs), in dB
>> %        freqs    = frequencies of spectra (Hz)
>>
>> i.e.
>>
>> [spectra, freqs] = spectopo(..
>>
>> will give you the spectra with the corresponding frequencies
>>
>> spectra(1, find(freqs >= 8 | freqs <=13))  should then give you the
>> alpha frequency band spectrum.
>>
>> hope it works
>> -Simon
>>
>> --
>> Simon-Shlomo Poil
>>
>> Neuronal Oscillations and Cognition Group (NOC)
>> Department of Integrative Neurophysiology (INF)
>> Center for Neurogenomics and Cognitive Research (CNCR)
>> Neuroscience Campus Amsterdam
>> VU University Amsterdam
>> De Boelelaan 1085, Room B-435
>> 1081 HV Amsterdam, The Netherlands
>>
>> E-mail: simonshlomo.poil at cncr.vu.nl
>> Phone: +31 20 5989408
>> Webpage: http://www.poil.dk/s and http://www.cncr.nl
>>
>>
>>
>> 2011/6/19 nikos dhmou <dhmoubagg at hotmail.com>:
>>> Hello, thank you for your answer my problem is how can i extract the
>>> alpha
>>> band power spectrum only from spectopo. I get a vector of spec of 513
>>> values
>>> when I use spectopo for a set of epochs in a condition which represent
>>> frequencies up to 250 hz.
>>> I only need to calculate this spec value for alpha band to get a mean of
>>> power spectrum in two certain channels only for alpha band. Sorry but Im
>>> novice in eeg programming power spectrum
>>>
>>> Thanks,
>>> nikos
>>>> From: simonshlomo.poil at cncr.vu.nl
>>>> Date: Sun, 19 Jun 2011 02:47:19 +0200
>>>> Subject: Re: [Eeglablist] Alpha power spectrum assymetry
>>>> To: dhmoubagg at hotmail.com
>>>>
>>>> Dear Nikos,
>>>>
>>>> You can, e.g., use either the 'spec' or 'pwelch' function. They will
>>>> both give you a full power-spectrum, which you then need to integrate
>>>> in the alpha frequency band.
>>>>
>>>> good luck
>>>> -Simon
>>>> --
>>>> Simon-Shlomo Poil
>>>>
>>>> Neuronal Oscillations and Cognition Group (NOC)
>>>> Department of Integrative Neurophysiology (INF)
>>>> Center for Neurogenomics and Cognitive Research (CNCR)
>>>> Neuroscience Campus Amsterdam
>>>> VU University Amsterdam
>>>> De Boelelaan 1085, Room B-435
>>>> 1081 HV Amsterdam, The Netherlands
>>>>
>>>> E-mail: simonshlomo.poil at cncr.vu.nl
>>>> Phone: +31 20 5989408
>>>> Webpage: http://www.poil.dk/s and http://www.cncr.nl
>>>>
>>>>
>>>> 2011/6/17 nikos dhmou <dhmoubagg at hotmail.com>:
>>>> > Hello, Im looking a way to calculate power spectrum for alpha band on
>>>> > a
>>>> > set
>>>> > of subjects on a set of epochs for two channels and compare anyone has
>>>> > any
>>>> > idea ? I use spectopo but it calculates spectrum untill 250 hz not
>>>> > alpha
>>>> > band. Another problem i have is that the spectrums if i calculate
>>>> > right
>>>> > give
>>>> > pretty much the same spectrum for different conditions but that doesnt
>>>> > make
>>>> > sense because i want to compare the spectrums for different conditions
>>>> >
>>>> > thanks for the help
>>>> > nikos
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>>>
>>
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>
>
>
> --
> Simon-Shlomo Poil
>
> Neuronal Oscillations and Cognition Group (NOC)
> Department of Integrative Neurophysiology (INF)
> Center for Neurogenomics and Cognitive Research (CNCR)
> Neuroscience Campus Amsterdam
> VU University Amsterdam
> De Boelelaan 1085, Room B-435
> 1081 HV Amsterdam, The Netherlands
>
> E-mail: simonshlomo.poil at cncr.vu.nl
> Phone: +31 20 5989408
> Webpage: http://www.poil.dk/s and http://www.cncr.nl
>
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-- 
Makoto Miyakoshi
JSPS Postdoctral Fellow for Research Abroad
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego