[Eeglablist] Alpha power spectrum assymetry

[Simon-Shlomo Poil]

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