How to edit y-axis scale in pop_spectopo function to log power spectral density 10*log10(uV^2/Hz)

I am trying to plot the average power spectrum for a group of participants. MatLab automatically uses a numeric scale for the yaxis, this can be changed to 'log' in the figure editor page but I want the y-axis to use the following scale: log power spectral density 10*log10(uV^2/Hz).

I am plotting an average power spectrum for one channel for a group of subjects.

This is my current code:

dataDir_1 = '/Users/juliannemcleod/Documents/Data1';
ch = 20; % ch is the number of channel you need
i = 1; %% i is the subject number


ch = 20;
setFiles_1 = dir(fullfile(dataDir_1, '*.set'));

for i = 1:length(setFiles_1)
    EEG1 = pop_loadset('filename', setFiles_1(i).name, 'filepath', setFiles_1(i).folder);
    spectrum_1(i,:) = pop_spectopo(EEG1, 1, [], 'EEG' , 'percent', 100, 'freq', [0 100], 'freqrange', [0 100], 'electrodes', 'off', 'plot', 'off', 'plotchans', ch);
end

figure;
plot(mean(spectrum_1,1));
xlim([0 100]); % Assuming you want frequencies from 0-100 Hz
xlabel('Frequency (Hz)');

Answer 1

[Star Strider]

This ‘10*log10(uV^2/Hz)’ is the same a dB/Hz. Thi is the same as the units of the ‘pxx’ outputs of the pwelch and periodogram functions. If your ‘pop_spectopo’ function uses one of those functions, no further conversion is necessary. Just set:

ylabel('PSD (dB\muV/Hz)')

or something similar.

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[Julianne]

Thank you!

[Star Strider]

My pleasure!

If my Answer helped you solve your problem, please Accept it!

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