[FieldTrip] using ft_topoplotER to plot selected FFT peak amplitudes over scalp?

[marek]

Dear all,

Is it possible to use ft_topoplotER to draw selected frequency peaks
over scalp after FFT analysis?

I did frequency analysis of EEG signal in the range 3-42 Hz with the
following settings:
cfg              = [];
cfg.output       = 'pow';
cfg.channel      = 'all';
cfg.method       = 'mtmfft';
cfg.taper        = 'hanning';
cfg.trials     = 'all';
cfg.keeptrials = 'no';
cfg.foilim     = [3 42];
fft1 = ft_freqanalysis(cfg, avg1);

I would like to draw a scalp distribution of FFT peaks for, say 20 Hz.
(I've got _only_ frequency domain data).

Is it possible to do it with with the ft_topoplotER function? What
settings are needed?
I tried it using cfg.ylim nor cfg.xlim parameters but they do not seem
to be related to the parameter (the frequency selection) I try to
manipulate.

Any help will be greatly appreciated!

Best,
Marek

Psychophysiology Laboratory,
Jagiellonian University, Krakow (PL)