Dear Andy,
thanks for your fast reply! Yes, images are realigned to the first images of their respective session and then aligned together from both sessions. But doesn’t that apply to movement parameters, too?
Sorry, I just do not get it right now….
Thank you again!
Dear Carmen,
If I understand correctly, images from each session are aligned to the first image of their respectively session first, then images from both sessions are aligned altogether.
That would explain the zeros at the head line of 2nd rp.txt.
Best,
Andy
On Fri, Mar 6, 2015 at 10:03 PM, Carmen <[log in to unmask]> wrote:
Dear SPM-experts,
I preprocessed 2 sessions of a subject registering to the first image (SPM12). As I expected, the first row of the rp.txt of the first session contains only zeros, as this is the “original position” of the subject. However, the rp.txt-file of the second session also begins with zeros.
For the second session, I would have expected numbers different from zero, as, if I understood correctly, everything is realigned to the first image and I thought movement is calculated with reference to the first image, too.
Could you please help me to understand this?
And moreover, is this a problem when concatenating sessions, e.g. for connectivity analysis?
Thank you very much,
Carmen
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