On Mon, Jan 10, 2011 at 6:01 PM, Maryann Martone <mary...
> Thanks Jyl. Definitions that I have been able to glean from various
> textbooks etc suggest that tracts are distinguished by having a common
> origin and common destination and are named accordingly, e.g., cortical
> spinal tract.
> Lemniscus according to one definition is used to describe flattened (i.e.,
> "ribbon") macroscopic white matter associated with ascending sensory
> Decussation is the crossing of fibers not connecting the same structures on
> both sides of the brain, as opposed to a commissure which connects the same
> structures on both sides. The decussation is certainly a site, i.e., the
> place where fibers cross, but the decussation also refers to the crossing
> fibers themselves.
> Pathways need not be macroscopically visible nor represent a bundle of
> axons, e.g., the perforant pathway.
> I'm all for simplifying the current mess according to Onard's suggestions.
> The idea is to make it computable. The preferred label can reflect the
> historic name, e.g., fasciculus, lemniscus.
> On Jan 10, 2011, at 2:37 PM, Jyl Boline wrote:
>> Hello All and welcome back from the holidays,
>> I haven't come up with any consensus definitions for nerve, nerve
>> fiber bundle, tract and pathway, because it seems this discussion
>> isn't finished yet. Clif has pointed out that nerves are considered
>> part of the PNS, while tracts and pathways are considered part of the
>> CNS (although these are not synonymous).
>> However, Onard brought up an interesting suggestion, which I hoped
>> people might weigh in on before we move forward. While some of the
>> names are a little different than the ones we're discussing, perhaps
>> we can create synonyms and also use this this structure to help us
>> organize. I've pasted Onard's suggestion below and all comments and
>> suggestions would be greatly appreciated. Thanks much!
>> Neural fiber bundle (aggregate or collection of axons in cord-like
>> - CNS fiber bundle -
>> ( Here we need to resolve what is the difference or what
>> are the similarities between, TRACT, FASCICULUS, LEMNISCUS, STRIA,
>> ANSA, FUNICULUS, DECUSSATION, RADIATION and PATHWAY. Which ones are
>> subtypes of another and which one are parts of another? E.g.
>> corticospinal TRACT has a part " pyramidal DECUSSATION segment of
>> corticospinal tract". Are they defined based on structural or
>> functional properties or both?)
>> - PNS fiber bundle
>> - Nerve trunk
>> -Cranial nerve trunk
>> -Spinal nerve trunk
>> -Nerve root
>> -Nerve rootlet
>> -Nerve cord (e.g. lateral cord of brachial plexus)
>> Nerve in the FMA is a neural tree which consists of root, trunk and
>> branches (each branch consists of its own trunk and its own set of
>> On Thu, Dec 16, 2010 at 2:56 PM, Mihail Bota <mbot...@gmail.com> wrote:
>>> Thank you for correction Dr. Saper.
>>> So, the criterion to dissociate a nerve from a tract is actually a
>>> structural one, not only a positional one - it is the type of the cell
>>> produces myelin.
>>> Can I ask for references regarding the myelinization of cranial nerves?
>>> we get this, then we can better answer the questions of Chris Mungall.
>>> On Thu, Dec 16, 2010 at 4:27 AM, <csa...@bidmc.harvard.edu> wrote:
>>>> Mihail, the optic nerve is not a nerve. It is a misnomer, because it is
>>>> CNS tract (it has central myelin). Nerves are PNS structures and have
>>>> peripheral myelin.
>>>> As for the olfactory nerve, this is a misnomer as well, but of a
>>>> kind, because there really is no olfactory nerve. There are olfactor
>>>> rootlets, which run from the olfactory epithelium, through the cribiform
>>>> plate, into the olfactory bulb, but then never form a distinct nerve
>>>> The thing that most neuroanatomy teachers point to when they teach the
>>>> cranial nerves is actually the olfactory tract, from the olfactory bulb
>>>> (which is already part of the CNS) to the basal forebrain.
>>>> Clifford B. Saper, MD, PhD
>>>> James Jackson Putnam Professor of Neurology and Neuroscience, Harvard
>>>> Medical School
>>>> Chairman, Department of Neurology
>>>> Beth Israel Deaconess Medical Center
>>>> 330 Brookline Avenue, Boston, MA 02215 USA
>>>> Phone: 617-667-2622; Fax: 617-975-5161
>>>> Email: csa...@bidmc.harvard.edu
>>>> Note: This message is confidential and may be legally privileged. It is
>>>> intended solely for the addressee. If you receive it in error, please
>>>> this message and notify the sender immediately. Any use by an unintended
>>>> recipient is prohibited.
>>>> From: Mihail Bota [mailto:mbot...@gmail.com]
>>>> Sent: Wednesday, December 15, 2010 8:52 PM
>>>> To: Chris Mungall
>>>> Cc: Jyl Boline; Maryann Martone; Saper,Clifford (Chief, BIDMC
>>>> Subject: Re: nucleus and ganglion
>>>> Very good questions!
>>>> Please see below some of my answers.
>>>> On Wed, Dec 15, 2010 at 5:25 PM, Chris Mungall <cjmung...@lbl.gov>
>>>> No answers, only questions and some exercises to help improve these
>>>> * can we list examples of each of these? E.g the cranial nerves.
>>>> --the list:
>>>> Also, FMC definition for nerves:
>>>> and for tracts
>>>> http://brancusi1.usc.edu/thesaurus/definition/white-matter-tract/ --
>>>> one answers, at least partially, to some of your questions.
>>>> See also the definitions of the vomeronasal nerve:
>>>> of the optic nerve:
>>>> As you'll see, some subparts of them have "tract" in their names.
>>>> Optic nerve and olfactory nerve are in CNS.
>>>> I'll think at the remaining questions.
>>>> * what are the relationships between these classes? Is NFB a superclass
>>>> both nerve and tract? If not, are they all mutually disjoint classes? I
>>>> presume not, but it's good to make all assumptions explicit
>>>> * are tract and nerve disjoint classes? I presume so based on the
>>>> distinction. Again, it's good to make this explicit
>>>> * can we avoid weasel-words like "largely"? Is there a tract that does
>>>> go from one CNS location to another? If so, mention it. If not, remove
>>>> * Are nerves always part_of the nervous system, or can they overlap with
>>>> the CNS? Is there a name for the structure that is a continuous
>>>> * Many AOs have a class "peripheral nerve" but treatment is
>>>> Can we come up with a good shared definition for this?
>>>> * FMA divides things into neural tree organs and segments of neural tree
>>>> organs. For example, cranial nerve II is not a subclass of cranial nerve
>>>> it's a subclass of nerve trunk, which is a subclass of segment of neural
>>>> tree organ. Do we want to adopt their definitions?
>>>> On Dec 15, 2010, at 10:27 AM, Jyl Boline wrote:
>>>>> Hello again All,
>>>>> So far we haven't had any feedback on our set of definitions having to
>>>>> do with nerves/tracts etc. This is what we have so far, but we're
>>>>> probably missing terms, and some of these may be synonyms. Please let
>>>>> me know your thoughts on these.
>>>>> 1) Bundles of axons located in the peripheral nervous system
>>>>> 2) Segment of neural tree organ which has as its direct proper
>>>>> parts a nerve trunk and its branches; together with other nerves of
>>>>> the same tree it constitutes a neural tree.
>>>>> Nerve fiber bundle:
>>>>> A fasciculated bundle of neuron projections largely or completely
>>>>> lacking synapses.
>>>>> A collection of axons that largely arises from one central nervous
>>>>> system part and terminates in another. Tracts are generally named by
>>>>> their region or origin followed by their region of primary
>>>>> termination, e.g., mammillothalamic tract contains axons that arise
>>>>> from neurons in the mammillary bodies and terminate in the thalamus.
>>>>> A collection of nerve fibers
>>>>> Thanks much!
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> Maryann Martone
> Dept of Neurosciences
> University of California, San Diego
> San Diego, CA 92093-0446
> Tel: 858 822 0745
> Fax: 858 246 0644
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