MVPaa: specifying subdivisions and searchlight analysis

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JonathanErez

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Aug 15, 2012, 2:39:31 PM8/15/12
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Hi Sasha,

 

I have two more questions about the MVPaa scripts, I’d appreciate any help!


1. I was wondering what is the difference between specifying different subdivisions and different sessions. 

For example, if my experiment has 3 conditions and is comprised of 4 sessions -- are different sessions treated as different subdivisions? In other words, should I be specifying my events as:


aap = aas_addevent(aap,’aamod_firstlevel_model’,’*’,’session1’,’condition1_sub1’,onsets.session{1}.condition1,0)

aap = aas_addevent(aap,’aamod_firstlevel_model’,’*’,’session1’,’condition2_sub1’,onsets.session{1}.condition2,0)

aap = aas_addevent(aap,’aamod_firstlevel_model’,’*’,'session1’,’condition3_sub1’,onsets.session{1}.condition3,0)

 

aap = aas_addevent(aap,’aamod_firstlevel_model’,’*’,’session2’,’condition1_sub1’,onsets.session{2}.condition1,0)

aap = aas_addevent(aap,’aamod_firstlevel_model’,’*’,’session2’,’condition2_sub1’,onsets.session{2}.condition2,0)

aap = aas_addevent(aap,’aamod_firstlevel_model’,’*’,’session2’,’condition3_sub1’,onsets.session{2}.condition3,0)

etc……

or:

aap = aas_addevent(aap,’aamod_firstlevel_model’,’*’,’session1’,’condition1_sub1’,onsets.session{1}.condition1,0)

aap = aas_addevent(aap,’aamod_firstlevel_model’,’*’,’session1’,’condition2_sub1’,onsets.session{1}.condition2,0)

aap = aas_addevent(aap,’aamod_firstlevel_model’,’*’,‘session1’,’condition3_sub1’,onsets.session{1}.condition3,0)

 

aap = aas_addevent(aap,’aamod_firstlevel_model’,’*’,’ session2’,’condition1_sub2’,onsets.session{2}.condition1,0)

aap = aas_addevent(aap,’aamod_firstlevel_model’,’*’,’ session2’,’condition2_sub2’,onsets.session{2}.condition2,0)

aap = aas_addevent(aap,’aamod_firstlevel_model’,’*’,’ session2’,’condition3_sub2’,onsets.session{2}.condition3,0)

etc….


(I’m specifying a [1 -1 -1; -1 1 -1; -1 -1 1] contrast following that)

 

2. For the Searchlight analysis:

aamod_MVPaa_brain_1st and aamod_MVPaa_brain_SPM seem to work fine -- but when I’m trying to view the results of my contrast in SPM, the entire resulting image is shifted to the left (on the glass brain), which makes me wonder whether the normalization in aamod_MVPaa_brain_SPM worked properly. I am doing something wrong?

 

Thanks!

Jonathan.

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