I can answer in greater detail later, but 1) you need to "hack" the stc object and figure out the right scale after putting the frequenies in .times and accordingly scale ; by default our data containers assume time domain data 2) if you use dSPM as method it is a pseudo F-statistic, for interpretable power plots you should use MNE as method in the inverse solver <br><br>I hope this helps a bit,<br><br>Denis<br><div class="gmail_quote"><div dir="ltr">On Thu, 30 Jun 2016 at 22:49, Gladia Hotan <<a href="mailto:gladiach@gmail.com">gladiach@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><span style="font-family:arial,helvetica,sans-serif">Hi,<br><br></span></div><div><span style="font-family:arial,helvetica,sans-serif">I have a couple of questions about the psd of sources:<br></span></div><div><span style="font-family:arial,helvetica,sans-serif"><br></span></div><span style="font-family:arial,helvetica,sans-serif">1) I used <br></span><pre style="background-color:rgb(255,255,255);color:rgb(0,0,0);font-size:9.6pt"><span style="font-family:arial,helvetica,sans-serif">stc = mne.minimum_norm.compute_source_psd<br></span></pre><pre style="background-color:rgb(255,255,255);color:rgb(0,0,0);font-size:9.6pt"><span style="font-family:arial,helvetica,sans-serif">to get an stc file containing the psd of the sources. It seems like in this stc file, <br>frequency has replaced time, but is still called 'time':<br><br><SourceEstimate | ... tmin : 0.0 (ms), tmax : 55.0 (ms), tstep : 0.25 (ms) ...><br><br>(I set the function to compute from 0 to 55 Hz; the time duration of the data is<br>actually a lot longer). I can use stc.plot or mne.plot_source_estimates to visualize this, but it treats <br>the frequencies like times. How can I plot the psd at a particular frequency on the brain? <br><br></span></pre><pre style="background-color:rgb(255,255,255);color:rgb(0,0,0);font-size:9.6pt"><span style="font-family:arial,helvetica,sans-serif">2) What are the units of the psd of the sources? According to the <a href="http://martinos.org/mne/stable/auto_examples/time_frequency/plot_source_power_spectrum.html#sphx-glr-auto-examples-time-frequency-plot-source-power-spectrum-py" target="_blank">tutorial</a> the psd is in dB,<br>but what is the reference quantity being used when converting to dB? (Ie. what is Pref in P_db = 10*log10(P/Pref)?)<br>Am I right that the source amplitudes are in units of ampere-metres?<br></span></pre><pre style="background-color:rgb(255,255,255);color:rgb(0,0,0);font-family:"DejaVu Sans Mono";font-size:9.6pt"><span style="font-family:arial,helvetica,sans-serif">Thanks and Best,<br>Gladia</span><br></pre></div>
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