[pymvpa] [PyMVPA] hevay head movements

Yaroslav Halchenko debian at onerussian.com
Fri Aug 22 01:40:50 UTC 2014

On Tue, 19 Aug 2014, cfygj wrote:
>    I want to conduct MVPA, and I have four runs data. Now I need to fslmerge
>    these four runs and make a common mask for them. The problem that I need
>    to address is that heavy head movements between these runs. That is to
>    say, each run has samll head movements, however, heavy head
>    movements would generate when fslmerge these 4 runs. How to remove the
>    possible effect of head motion on BOLD signal. Anyone have the quick
>    answer on this?

you just motion correct all of your BOLD runs (after fslmerge, do not
motion correct before at all) to a sample image taken from one of
your runs (at times, closest to the anatomical, i.e. from the last run
if anatomical is taken after).  Some people do it multi-pass even: after
initial pass of motion correction take the mean of all motion corrected
volumes from all runs as you target image and motion correct original 4
runs to that one.

hope this helps
Yaroslav O. Halchenko, Ph.D.
http://neuro.debian.net http://www.pymvpa.org http://www.fail2ban.org
Research Scientist,            Psychological and Brain Sciences Dept.
Dartmouth College, 419 Moore Hall, Hinman Box 6207, Hanover, NH 03755
Phone: +1 (603) 646-9834                       Fax: +1 (603) 646-1419
WWW:   http://www.linkedin.com/in/yarik        

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