[FieldTrip] Source statistic doesn't match grand average difference at all and prior knowledge

[Haiteng Jiang]

Hi FTer,
   I am  doing Cluster-based permutation statistic  after beamforming on
two condition over subjects following the tutorial
http://fieldtrip.fcdonders.nl/example/source_statistics, but I get
something funny.
 In my case , I would expect decreased activity in  the visual and
posterior area.  The effect is quite strong, which  is showed in the grand
average  difference (log ratio to reduce inter subject variability).
 However ,  from the statistic ,  the identified areas go to  the temporal
area , which doesn't make sense at all .   Please see the below and
attached  pictures.    I understand cluster-based permutation  test doesn't
necessary pick the peak difference, but  in general it should find main
different area.  Any comment would be greatly appreciated.

Average:

[image: Inline images 2]



Statistic:
[image: Inline images 1]

 Best,

 Haiteng

-- 
Haiteng Jiang
PhD candidate
Neuronal Oscillations Group
Donders Institute for Brain, Cognition and Behaviour
Centre for Cognitive Neuroimaging
Radboud University Nijmegen

Visiting address
Room 2.32
Donders Centre for Cognitive Neuroimaging
Kapittelweg 29
6525 EN  Nijmegen
the Netherlands

 Tel.: +31 (0)243668291
 Web:  https://sites.google.com/site/haitengjiang/
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