[Marsbar-users] how to using Conjunction analysis to define ROI

[chunhong <chu...@gm...>]

Hi MarsBar users,

I'm new to Marsbar. I want to use the activation of conjunction analysis
to define ROI. I used the procedure in the following way:

First I created a binary mask for the conjunction image in below way:
               MarsBar--> Definition-->Build
                   -->Type of ROI -->image (selecting conjunction image)
                     --> maintain as binary mask?---Yes
                     --> apply function to image? ---> Yes
                     --> function to apply to image-->img > 0.0
                     --> description of ROI--> whatever I like
                       --> label for ROI--> whatever I like
                       --> save to whatever directory I want

Then combine this binary mask with whatever predefined MNI.roi in AAL
together as follows:
         MarsBar -> ROI definition-> Transform -> Combine ROI (r1 & r2)
                -->selecting conjunction image I just created and    
                MNI.roi in AAL which I'm interested in, such as SFG_L  
                                
                        --> Function to combine ROI: r1 & r2
                                        --> Description of ROI: eg.SFG_L
                                        --> Label of ROI: eg.SFG_L
                                        --> Save

After that, MarsBar-> Definition->to view the combination. Using this to
determine a x,y, z coordinates to define my ROI. Should anyone tell me
procedure above is correct? if not, what should I do?

Also, I found the combination is a range. Should I use the numbers of
"centre of mass" as x,y,z coordinates or pick up whatever numbers of the
crosshair is pointing (which is still in the range)? Thanks in advance!

Regards,

-- 
Chunhong Shao
cs...@pu...
Research Associate 
Department of Psychological Sciences
Purdue University