[Mne_analysis] Alarmingly similar results for subcortical source activity

[Alan]

Hello,

I've been looking at right amygdala activity in the spm faces dataset as a
means of developing subcortical source localization tools. I've tried two
different methods so far.

1.) I did a whole brain volume analysis (dSPM) and then averaged together
vertices belonging to the right amygdala (code here
<https://github.com/leggitta/PythonEEG/blob/master/spm_volume.py>).

2.) I merged the left and right cortical surface source spaces with a right
amygdala volume source space, performed dSPM and then averaged together the
volume sources (code here
<https://github.com/leggitta/mne-python/blob/gsoc-subcortical/examples/inverse/plot_subcortical_activation.py>).


I've attached the evoked plots for each condition (grey bars indicate
regions of significant difference using independent t-tests per time point
with fdr correction).

The results of each method are so similar that I'm concerned they may be
derived from a common source of error. Can anyone think of think of any
probable sources of error and suggest other ways to validate these methods?
I haven't yet ventured into simulated data, but I think that's going to be
the next step.

Thanks!
Alan
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