Dave,

You may need to select View->Information->MNI, which will enable an MNI Talairach coord entry box. MNI Tal differs from Tal in the z direction to correct for differences between the mni talairach-ized brain and real tal coords.

Nick

On Wed, 2009-01-28 at 11:23 -0500, Dave Brohawn wrote:

Hello,

I am having an issue with a discrepancy between talairach coordinates I plug into tkmedit tool bar, and what gets displayed when I generate a time course for this voxel.

FREESURFER_HOME: /usr/local/freesurfer/stable4

Build stamp: freesurfer-Linux-centos4-stable-v4.2.0-20090128

RedHat release: CentOS release 4.6 (Final)

Kernel info: Linux 2.6.9-67.ELsmp i686

NMR Center info (/space/freesurfer exists):

machine: seymour

SUBJECTS_DIR: /space/seymour/4/users/joshdata/

PWD: /space/seymour/4/users/joshdata

When I generated the time course. the overlay I loaded onto the orig volume is

/space/seymour/4/users/joshdata/CC-n8_fixed/bold/EMerror/tal-ffx/ASevfix/cespct.bhdr.

Registration file is: /space/seymour/4/users/joshdata/CC-n8_fixed/bold/EMerror/tal-ffx/register.dat.

The voxel I want to generate a time course for has these coordinates: X -3.96 Y - -20.22 Z - -15.81

When I plug these into the tkmedit tool bar, the emerging time course graph has coordinates X- -4.00 Y - -20.00 Z- -20.00.

While the X and Y coordinates are close enough, the Z is off.

If I change the Z coordinate in the toolbar to -12.3, it will give me a -15. 8 value for the Z coordinate on the time course plot caption.

Is this image legitimate? Which image accurately represents the original coordinates I want to use?

Please write back when you can, and thank you,

Dave Brohawn

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