Dear FreeSurfers,

I have a question concerning the morphological correspondence between the tracts obtained with the old version of Tracula, which reconstructs 18 white matter tracts, and the new version of Tracula, which reconstructs 42 white matter tracts.

In the old version, FreeSurfer website specified the orientation of tracts as followed

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Points are always ordered in the following way:

• CST : Brainstem -> Motor cortex

• UNC : Temporal -> Orbitofrontal

• ILF : Temporal -> Occipital

• ATR : Frontal cortex -> Thalamus

• CCG (CingulumCingGyrus) : Posterior -> Anterior

• CAB (CingulumAngBundle) : Posterior -> Anterior

• SLFP : Frontal -> Parietal

• SLFT : Frontal -> Temporal

• F-MAJOR/MINOR : Left -> Right

compared to the new orientation also specified in the website

Points are ordered according to the following convention (see also along-tract plots):

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For pathways with a right-left orientation:

If the pathway is inter-hemispheric: From right to left

If the pathway is intra-hemispheric: From medial to lateral

For pathways with an anterior-posterior orientation: From anterior to posterior

For pathways with a superior-inferior orientation: From superior to inferior

I have post-processed my data with the old version and I'm concerned specifically with two tracts, ATR and CCG. Theoretically, ATR has the same orientation in both versions, antero-posterior, from frontal lobe to thalamus, but the FA graph created by voxel-data obtained with the old version has an inverted morphology, meaning that the highest values of FA in the old version are placed in the anterior limb of internal capsule whereas the highest values of FA in the new version are located in the frontal lobe. To make it clear, I will send you attached a pdf.

Regarding CCG, the FA graph created by voxel-data obtained with the old version has the same morphology, when I will expect the inverted morphology given that the new orientation (antero-posterior) is inverse to the old orientation (postero-anterior).

The other tracts of the old version have a concordance with the tracts of the new version.

I would be very grateful if someone could tell me if I can trust the data obtained with the old version and the graphs obtained with by-voxel data.

Thank you in advance.

Montse Domingo Ayllón