[FieldTrip] Opposite DICS Beamforming results on source and sensor level on resting state data
Haiteng Jiang
haiteng.jiang at gmail.com
Mon Jan 5 15:23:20 CET 2015
Hi all,
I performed DICS beamforming on resting-state data ( eyes closed) of a
clinical population and controls. According to the sensor data, the
control groups have more alpha-band (8-14
Hz) activity over occipital areas after cluster statistic (attached
figure upper plot) . Curiously, after beamforming , group comparisons
showed the reversed patters in visual cortex (attached figure bottom plot)
.Hence, the source-level results are opposite to the sensor-level results.
This is *not* a problem of the design matrix, or confusing the groups. I
check the individual neural activity index on the single subject level .
They make sense in general . I also tune the parameter a lot (tapper,
central frequency smooth frequency , regularization parameter , et al ),
the opposite pattern remains. I understand that Beamformer images DO NOT
DIRECTLY CORRESPOND TO ANY sensor data. However, the opposite pattern is
really weird. I noticed that Tobias Navarro Schröder had the similar
issue 4 years ago (
http://mailman.science.ru.nl/pipermail/fieldtrip/2011-May/003875.html).
Thus, I am not the only one who encountered this problem.
Any tips and suggestions will be greatly appreciated. Thanks in advance!
Best,
Hatieng
--
Haiteng Jiang
PhD candidate
Donders Institute for Brain, Cognition and Behaviour
Neuronal Oscillations Group
Computational Cognitive Neuroscience Lab
https://sites.google.com/site/haitengjiang/
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