<div dir="ltr"><div>Dear Teon,<br><br></div>As I understand, power.plot_topo plots changes relative to the baseline if you use the 'logratio' or 'zscore' options. <br><br>
<p style="margin:0px;text-indent:0px">E.g.: .... z-score (power is divided by standard deviation of power during baseline after subtracting the mean,
</p><p style="margin:0px;text-indent:0px"> power = [power - mean(power_baseline)] / std(power_baseline))....</p><p style="margin:0px;text-indent:0px"><br></p><p style="margin:0px;text-indent:0px">So, if power_baseline>power, there should be negative values irrespective the channel type. This is not the case.</p><p style="margin:0px;text-indent:0px"><br></p><p style="margin:0px;text-indent:0px">Elena<br></p><p style="margin:0px;text-indent:0px"><br></p><p style="margin:0px;text-indent:0px"><br></p><div class="gmail_extra"><br><div class="gmail_quote">On 31 March 2015 at 17:17, Teon Brooks <span dir="ltr"><<a href="mailto:teon.brooks@gmail.com" target="_blank">teon.brooks@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hi Elena,<br><br>Gradiometers only measure amplitude changes in the magnetic field and do not have a direction associated with them. For the magnetometers, they will have the magnitude and directions. <br><br>HTH,<br>Teon<br><div class="gmail_quote"><div><div class="h5">Le mar. 31 mars 2015 à 17:10, Elena Orekhova <<a href="mailto:orekhova.elena.v@gmail.com" target="_blank">orekhova.elena.v@gmail.com</a>> a écrit :<br></div></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><div class="h5"><div dir="ltr"><div><div><div><div><div><div>Hello!<br><br></div>I noticed that power.plot_topomap <br><br>[example in <a href="http://martinos.org/mne/stable/auto_examples/time_frequency/plot_time_frequency_sensors.html#example-time-frequency-plot-time-frequency-sensors-py" target="_blank">http://martinos.org/mne/stable/auto_examples/time_frequency/plot_time_frequency_sensors.html#example-time-frequency-plot-time-frequency-sensors-py</a> ] <br><br>only plots positive values. It does so even if I clearly see alpha suppression (see the attached plot) and use 'logratio' option.<br></div></div><br>The command I use is:<br>
<p style="margin:0px;text-indent:0px">power.plot_topomap(ch_type='grad', tmin=0.4, tmax=1.0, fmin=7, fmax=15, baseline=(-0.5, -0.1), mode='logratio', axes=axis[0],
</p><p style="margin:0px;text-indent:0px"> title='Alpha')</p><br></div>What can be the problem?<br><br></div>Regards,<br></div>Elena<br><div><div><div><div><div><br></div></div></div></div></div></div></div></div>
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