Re: [Marsbar-users] using conjunction activation to define ROI

[Matthew B. <mat...@gm...>]

Hi,

> First I created a binary mask for the conjunction image in the way below:
>                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

Looks reasonable.

> 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

Yup - which will give you the overlap between the ROIs.

> 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!

Well - the combination gives you an ROI - isn't that what you want
rather than the centre of mass or something?  But if you do need a
sphere for some reason, I guess the centre of mass is a good choice.

Best,

Matthew