# [Eeglablist] Freq power baseline question

Scott Makeig smakeig at ucsd.edu
Sat Nov 2 14:01:34 PDT 2019

```Dave -  Your msg has indeed appeared on the eeglablist 4 times... Spectopo
does not subtract a (log) baseline. The function newtimef() computes
event-related spectral perturbations (ERSPs).

Scott Makeig

On Tue, Oct 29, 2019 at 12:41 PM David Ryan <ryand1 at goldmail.etsu.edu>
wrote:

> Hello,
> I have sent this email to the listserv several times, gotten a
> confirmation email but never saw it in the listserv. Do I need to
> correct something?
>
> Thanks,
> Dave
>
>
> Hello,
>
> I am looking into frequency power changes with the onset of an
> auditory stimulus and a time window of 0-700ms utilizing the script
> below. Does this process baseline correct? Does it need a baseline
> correction?
>
> [spectra,freqs] = spectopo (EEG.data(Fz,:,:), 0, EEG.srate);
>
> %Data ranges
> hz8 = find(freqs>7 & freqs<9);
> hz7 = find(freqs>6 & freqs<8);
> hz6 = find(freqs>5 & freqs<7);
> hz5 = find(freqs>4 & freqs<6);
> hz4 = find(freqs>3 & freqs<5);
>
>
> % Compute Power
> hz8powerFz = 10^(mean(spectra(hz8))/10);
> hz7powerFz = 10^(mean(spectra(hz7))/10);
> hz6powerFz = 10^(mean(spectra(hz6))/10);
> hz5powerFz = 10^(mean(spectra(hz5))/10);
> hz4powerFz = 10^(mean(spectra(hz4))/10);
>
>
> Thanks,
> Dave
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--
Scott Makeig, Research Scientist and Director, Swartz Center for
Computational Neuroscience, Institute for Neural Computation, University of
California San Diego, La Jolla CA 92093-0961, http://sccn.ucsd.edu/~scott
```