[Mne_analysis] Topoplot

[JR KING]

Hi Jeff,

Could it be that your topos are combined gradiometers (and are thus squared
and positive), whereas the time freqs are all sensors?

(By the way, cmap='jet' is not recommended:
https://jakevdp.github.io/blog/2014/10/16/how-bad-is-your-colormap/)

JR

On 21 February 2018 at 11:32, Stout, Jeffrey <jstout at mcw.edu> wrote:

> 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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