I am not an expert but I'll say this as far as compliance to Duvernoy: In the body of the hippocampus, compliance to Duvernoy is quite strong....much better than any others I've seen. However, according to my reading of Duvernoy, the positions of the subfields change in the anterior head and posterior tail, as compared to the body. Subiculum comes farther laterally, and CA1 is further up superior-lateral (about at 10:00 o'clock), and proceeds superiorally of the hippocmapus almost to the most medial extent of the hippocampus...leading me to conclude that CA3 is very small in the head, and may be non existent in the most anterior half of the head....at least according to my reading of Duvernoy atlas.

I want to reiterate my support for this project. The hippocampal subfields are very important to a great number of researchers, as are the other MTL structures (i.e. perirhinal cortex, posterior parahippocampal gyrus, entorhinal cortex). By implementing an easy to use automated technique, Freesurfer will, in my estimation become the de-facto standard in the field. As such, I believe the segmentation protocol will come under increased scrutiny by the community...and I wish that an effort is made by someone (like Duvernoy but more robustly quantified) to create a standard that is well validated by which all researchers may begin making comparisons of their findings. The current Freesurfer implementation does a pretty good job...but the field needs to come to terms with the positions of the fields, and how those might change along the long-axis of the hippocampus.

Best,

Joshua

n Thu, Jan 26, 2012 at 8:50 AM, Joana Braga Pereira <jbragapereira@gmail.com

wrote:

Dear Koen,

Thanks! I will wait for Dr. Augustinack and Dr. Dickerson's answers.

joana

2012/1/26 Koen Van Leemput koen@nmr.mgh.harvard.edu

...

Hi Joana,

The smallness of our CA1 compared to other protocols seems to be caused by disagreements in the fields of where the subfield boundaries should be located. I've talked to several experts on this and they all are confident that their own definition is the only "right" one. :-)

As for the atlas our manual segmentations are based on, I believe it's Duvernoy but I'm cc-ing Jean Augustinack and Brad Dickerson who know more about this.

Hope this helps,

Koen

On Thu, Jan 26, 2012 at 9:54 AM, JOANA BRAGA PEREIRA jbragapereira@ub.edu wrote:

...

Dear Koen & Freesurfers,

I've been working with the GEMS tool for hippocampal subfields segmentation and have a question I would like to ask you all.

I've noticed that the CA1 sector appears to be quite small compared to other subfields (CA2-3 seems to be the largest), while previous studies suggest that it should be the largest subfield of the hippocampus. Why?

On the other hand, I have read the paper by Van Leemput et al. [2009] and how the subfields were initially delineated and was wondering what atlas was the manual tracing based on?

Many thanks!

joana

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