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<p>Dear Makoto,<br>
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<p>I have a doubt for the power unit. I read the "help spectopo" in Matlab, for the variable "spectra":<br>
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<div>Outputs:</div>
<div> spectra = (nchans,nfreqs) power spectra (mean power over epochs), in dB</div>
<div> freqs = frequencies of spectra (Hz)<br>
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<div>If the unit of variable "spectra" is in dB unit already, then when computing the absolute power, do we still need to do the transformation as you suggested (i.e.
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10.^(spectra(deltaIdx)/10)</span>)? <br>
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<div>I know when plotting the figure, the spectrum is plotted in log scale. But if the unit of spectra is in dB, then there's no need to transform, right? <br>
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<div>I don't know if this is correct... Could you look more into it? Thank you so much!!<br>
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<div>Shan Xin<br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> Makoto Miyakoshi <mmiyakoshi@ucsd.edu><br>
<b>Sent:</b> Thursday, 16 April 2015 11:11 AM<br>
<b>To:</b> #SHAN XIN#<br>
<b>Cc:</b> eeglablist@sccn.ucsd.edu<br>
<b>Subject:</b> Re: [Eeglablist] How can I get the power of each frequency band?</font>
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<div><span style="color:rgb(0,0,0); font-family:Calibri,Arial,Helvetica,sans-serif; font-size:16px">Dear Shan,</span></div>
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<div><span style="color:rgb(0,0,0); font-family:Calibri,Arial,Helvetica,sans-serif; font-size:16px"><br>
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> I'm not very proficient in Matlab programming...</span><br>
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<div class="gmail_extra">This could be a concern but you can try!</div>
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<div style="font-size:12.6666669845581px">%%%%%%%%%%%%%%%%%%%</div>
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<div>% for your epoched data, channel 2</div>
<div>[spectra,freqs] = spectopo(EEG.data(2,:,:), 0, EEG.srate);</div>
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<div>% delta=1-4, theta=4-8, alpha=8-13, beta=13-30, gamma=30-80</div>
<div>deltaIdx = find(freqs>1 & freqs<4);</div>
<div>thetaIdx = find(freqs>4 & freqs<8);</div>
<div>alphaIdx = find(freqs>8 & freqs<13);</div>
<div>betaIdx = find(freqs>13 & freqs<30);</div>
<div>gammaIdx = find(freqs>30 & freqs<80);</div>
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<div><font color="#ff0000">% compute absolute power</font></div>
<div><font color="#ff0000">deltaPower = mean(10.^(spectra(deltaIdx)/10));</font></div>
<div><font color="#ff0000">thetaPower = mean(10.^(spectra(thetaIdx)/10));</font></div>
<div><font color="#ff0000">alphaPower = mean(10.^(spectra(alphaIdx)/10));</font></div>
<div><font color="#ff0000">betaPower = mean(10.^(spectra(betaIdx)/10));</font></div>
<div><font color="#ff0000">gammaPower = mean(10.^(spectra(gammaIdx)/10));</font></div>
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<div>%%%%%%%%%%%%%%%%%</div>
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<div>Makoto</div>
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<div class="gmail_extra"><br>
<div class="gmail_quote">On Tue, Apr 14, 2015 at 6:23 AM, #SHAN XIN# <span dir="ltr">
<<a href="mailto:SHAN0055@e.ntu.edu.sg" target="_blank">SHAN0055@e.ntu.edu.sg</a>></span> wrote:<br>
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<p><span style="font-size:12pt">Hi EEGLab team,</span></p>
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Does EEGlab has plugin or script so that I can get the power of individual band (e.g. power of alpha band or beta band) from your computation, instead of just a continuous line in the power spectrum figure? I'm not very proficient in Matlab programming...t<span style="font-size:12pt">hank
you so much!!</span></div>
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<div>Best wishes,<br>
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<div>SHAN Xin<br>
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-- <br>
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<div dir="ltr">Makoto Miyakoshi<br>
Swartz Center for Computational Neuroscience<br>
Institute for Neural Computation, University of California San Diego<br>
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