[Mristudio-users] Fwd: Does the inferior fronto-occipital fasciculus exists?

[susumu mori]

"Atlantis" is a good one.

Just want to add a couple of things.

First of all, pixel-by-pixel evaluation of DTI, like define ROIs on FA maps
or inspect color maps, and tractography results are very different things.

As for the pixel-by-pixel evaluation, there are a cluster of pixels
currently named as IFO in our atlas. So, it is a real entity (not Atlantis).
Then the issue here is whether it is appropriate to call this location IFO.
This is an issue of nomenclature as well as interpretation.

As for the tractography, the reconstructed trajectory convincingly shows
that so-called "IFO" travels between the frontal and occipital lobes, just
like past histology sections have shown. However, it is a very valid
argument that there is actually not axons that travel the entire length of
the "IFO". In this case, the connection called IFO is "Atlantis". It seems
there, reported numerous times, but actually doesn't exist.

s


On Wed, Feb 23, 2011 at 2:30 AM, Naama Barnea-Goraly <naamab at stanford.edu>wrote:

>
> Dear Susumu,
>
> Thank for the informative response. In this case, Schmahmann and Pandya
> would argue (I think) that it is not about a "road description" or a "map
> description". To use your "Baltimore" analogy they might say the IFOF is
> "Atlantis": We don't know where it is, and it probably doesn't exist,
> although it has been described in ancient times.
> In their book section about the IFOF (labeled "Identification of the
> apparently non-existent IFOF") they say there are no "substantial direct
> anatomical connections between the inferior occipital lobes and the ventral
> prefrontal cortex" and that fibers referred to as the IFOF are in fact
> either the uncinate or the extreme capsule. They base their claims
> on isotope anterograde tract tracers.
>
> Attached are the relevant pages from their book and a paper they wrote a
> year later talking about the FOF (they say SFOF and IFOF should not be
> used). On the other hand, the IFOF is often mentioned and demonstrated in
> DTI and dissection studies so it does seem like a controversial topic. I
> agree with you that it is a nomenclature issue as there are fibers there.
>
> As you suggested, neuroanatomists should consider a meeting to discuss
> current knowledge of white matter brain pathways and naming conventions for
> white matter tracts.
>
> Thanks,
>
> Naama
>
>
>
>
>
>
> On Feb 18, 2011, at 4:59 PM, susumu mori wrote:
>
> Hi Naama,
>
> This is a good question and please allow me to share my though with people
> in the MriStudio mailing list.
>
> When we describe white matter, there are two ways. Let me use the analogy
> of geological maps. If I see a map of Baltimore, there are essentially two
> types of information; boundaries that define boarders of locations like
> city, county, and state. The other is road information like route 95 that
> travels from Washingon DC to NY. The former defines locations and the latter
> doesn't belong to any single location.
>
> Likewise, WM map has two ways to define. Many WM names define locations,
> like the internal capsule, which is a WM location between the basal ganglia.
> There are many "roads" that penetrate the internal capsule like
> cortico-thalamic, thalamo-cortical, cortico-spinal, cortico-pontine, to name
> few, but they are all intermingled and it's not possible to completely
> decipher them, at least by DTI/MRI. There are also names of WM that imply
> something similar to the road names. For example, the corticospinal tract
> and IFO defines two destinations.
>
> Our atlas obviously defines locations; all segments are defined by
> boarders. Some of the defined locations have names that implies roads (e.g.
> IFO, SFO, CST, ets), but they actually define locations. This is one source
> of confusion.
>
> Now, there are some more confusing things. I believe many macroscopic
> anatomical nomenclature is based on classic histology observations. The SFO
> and IFO are assigned to large white matter bundles that sweep from front to
> back, which look like connecting the frontal and occipital lobes, but I
> don't think it was confirmed that there are actually axons connecting the
> frontal and occipital lobes. Therefore, the foundation of the assigned names
> are not as sound as the corticospinal tracts, which are confirmed in many
> animals and human.
>
> Now, we assigned some locations of the brain "SFO" and "IFO". There is not
> doubt that there are large axonal bundles travelling front to back (or back
> to front) in the designated locations. However, if one asks, "do you know if
> these locations really contain axons connecting the frontal and occipital
> lobes?", well, I must say, "not sure". To me, it seems like an issue of
> nomenclature.
>
> In any case, assignments of "road-type" names to the WM is a tricky effort
> because even for the "corticospinal tract", the designated locations may
> contain many other axons like cortico-pontine and cortico-bulbar axons. As
> long as they are mixed in a microscopic level, we can only say, "this region
> has high concentration of the corticospinal tract" and, to be strict, we can
> always argue that it is not correct to give a binary definition to a place
> like, "this is the corticospinal tract", because the "real" corticospinal
> tract refers to axons that connect the cortex and the spinal cord, not to
> many millimeters of anatomical locations visualized by MRI/DTI.
>
> So, going back to your original question, there were controversy over the
> existence of SFO and now IFO . In these cases what is discussed is "is there
> really a large concentration of axons that connect the frontal and occipital
> lobes in the WM locations called SFO/IFO?" How does it affect our study?
> Well, for the IFO, maybe we should change the name of the location to "a
> large WM bundle running front-back (green color) at the junction of the
> frontal lobe and the temporal lobe". To me, the source of the problem is the
> adoption of road names to refer to locations. As long as we use our atlas to
> define locations and do quantitative measurements such as volumes and FAs,
> how we call each location is not really a critical issue. Of course, it
> could profoundly affect the interpretation. If the FA of "IFO" is low, we
> should not immediately conclude connectivity problems between the frontal
> and occipital lobes, simply based on the name of the location. In this
> sense, you raised an important issue. On the other hand, IFO/SFO have been
> widely used to refer some specific locations and we can communicate about
> anatomical locations through these terms. So, even if they
> are mis-nomenclature, we may need to keep using them unless the anatomist
> society comes up with a new set of anatomical languages to refer these
> anatomical locations.
>
> Susumu
>
> On Fri, Feb 18, 2011 at 5:07 PM, Naama Barnea-Goraly <naamab at stanford.edu>wrote:
>
>>
>> Dear Susumu,
>>
>> A recent analysis we are running yielded some significant results in the
>> IFOF (according to the JHU White matter tractography atlas) which lead me to
>> some investigation on this pathway. I was very surprised to read in " White
>> matter of the Brain" ( a book by Schmahmann and Pandya), that in fact the
>> IFOF does not exist (page 445). They think the IFOF is in fact the ILF
>> /uncinate/extreme capsule mistaken by early anatomists as a separate tract.
>> What do you think?
>>
>> Thanks,
>>
>> Naama
>>
>>
>>
>> Naama Barnea-Goraly M.D.
>> Instructor
>> Center for Interdisciplinary Brain Sciences Research
>> Stanford University Division of Child and Adolescent Psychiatry
>> 401 Quarry Rd. MC 5795
>> Stanford University School of Medicine
>> Stanford, CA  94305-5795
>> Phone: (650) 736-1874, fax: (650) 724-4794
>>
>>
>> CONFIDENTIALITY NOTICE:  This e-mail communication and any attachments may
>> contain confidential information for the use of the designated recipients
>> named above.  If you are not the intended recipient, you are hereby notified
>> that you have received this communication in error and that any review,
>> disclosure, dissemination, distribution or copying of it or its contents is
>> prohibited.  If you have received this communication in error, please notify
>> Stanford Medical Center immediately by telephone at (650) 725-5722 and
>> destroy all copies of this communication and any attachments.  Thank you.
>>
>>
>>
>>
>
> Naama Barnea-Goraly M.D.
> Instructor
> Center for Interdisciplinary Brain Sciences Research
> Stanford University Division of Child and Adolescent Psychiatry
> 401 Quarry Rd. MC 5795
> Stanford University School of Medicine
> Stanford, CA  94305-5795
> Phone: (650) 736-1874, fax: (650) 724-4794
>
>
> CONFIDENTIALITY NOTICE:  This e-mail communication and any attachments may
> contain confidential information for the use of the designated recipients
> named above.  If you are not the intended recipient, you are hereby notified
> that you have received this communication in error and that any review,
> disclosure, dissemination, distribution or copying of it or its contents is
> prohibited.  If you have received this communication in error, please notify
> Stanford Medical Center immediately by telephone at (650) 725-5722 and
> destroy all copies of this communication and any attachments.  Thank you.
>
>
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.mristudio.org/pipermail/mristudio-users/attachments/20110223/75888913/attachment-0001.html