[Mne_analysis] Topoplot

[Stout, Jeffrey]

MNE group,

When I plot the time frequency display, I predominantly get beta desynchrony with a strong negative z-score (using power.plot_topo).  When I plot that same data using the topomap (power.plot_topomap) and selecting the appropriate frequencies and time latencies the data appears as a positive Z-score.  Is there a sign flip during the topomap plotting and is there a flag to set to prevent the flip?

Attached are the outputs of the code below.  The data frequencies are 20-25Hz to highlight the difference in plots.  Data is from a Neuromag system  - using the gradiometers only.

Some code:
freqs = np.logspace(*np.log10([20, 25]), num=20)
n_cycles = freqs / 2.  # different number of cycle per frequency
power_3, itc = tfr_morlet(epochs['3'], freqs=freqs, n_cycles=n_cycles, use_fft=True,
                        return_itc=True, decim=3, n_jobs=-1)
power_2, itc = tfr_morlet(epochs['2'], freqs=freqs, n_cycles=n_cycles, use_fft=True,
                        return_itc=True, decim=3, n_jobs=-1)

power_minus=copy.copy(power_3)
power_minus._data=power_3._data - power_2._data
##### TOPOPLOT#######
tf_plot=power_minus.plot_topo(baseline=(-0.5, 0), mode='zscore', title='Average power', vmin=-10, vmax=10, tmin=-.1, tmax=.9, cmap='jet')

timepoints=[-.1,.1,.3,.5,.7,]
fig, axis = plt.subplots(1, len(timepoints), figsize=(20,3))
for i,laten in enumerate(timepoints):
####TOPOPLOT MAP######
    power_minus.plot_topomap(ch_type='grad', tmin=laten, tmax=laten+.1,  fmin=20, fmax=25,
                       baseline=(-0.5, 0), mode='zscore', axes=axis[i],
                       vmin=-10, vmax=10, show=False, cmap='jet', title=str(laten))
mne.viz.tight_layout()
plt.show()


Thanks,
Jeff Stout
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