Dear all,
We ran an experiment on a GE3T where pairs video-clips (each lasting 2s) were
presented with an ISI of 100ms. ITI between video-pairs was jittered.
After running few SPM8 analyses, we realized that the second video of the pair
presents activations that, I would say, are complementary to those observed in
the first video. E.g., an extended occipital activation observed in the first
video is replaced by the activation of cuneus/precuneus in the second video, and
so forth for all lobes.
Few causes can be excluded: A protocol problem, since we previously ran this
same study with a Siemens3T elsewhere and activations of first and second videos
were very similar. On very few numbers of participants of the present study, we
do observe a typical activation pattern; An onsets problem, since we ran a batch
file identical for all participants, and we did check the onsets manually as
well.
This 'complementary' activity is observed on a number of participants and we are
really struggling trying to understand why it is so. Could it relate to some
physical properties of this particular scanner (susceptivity, sensibility,
etc.)? Or shall we look at some other issue?
Thank you.
Cinzia
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