Electrode Trajectory

[markus.fahlstrom]

Hi Andy,

I’m looking to get the MNI coordinates for the most distal part of the electrode – segmented by Lead-DBS.
For all segmentations, the software stops at Z = -15.5 mm, as you have described in your article. But those the software always do this? And if I would like the coordinate for the electrode, where in the reconstruction matrix should I look since it always goes to -15.5?

And do you now any MNI atlas defining Zona Incerta?

Regards
Markus

[andreashorn]

Hi Markus,

the algorithm stops at -15.5 mm but that is just a line of the electrode trajectory, it doesnt say anything about the electrode position itself. You can use the coordinate of the lowermost contact (e.g. for right hemisphere stored as reco.mni.coords_mm{1}(4,:) in ea_reconstruction.mat – {2} is left hemisphere). Based on the next contact (coords_mm(3,:)) you could then easily compute the position of the tip (if you have the electrode dimensions).

For zona incerta I only know the Chakravarty atlas but it features the whole thing (not caudal ZI – handled as target for PD by e.g. Blomstedt/Plaha (but see Schmitz-Hübsch 2015 MDS and Welter 2014 Neurology) or the “zona incerta” some people refer to as the subthalamic area – handled as target for ET).

Hope that helps!

Best, Andy

[Author]

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