white matter/gray matter

[Alan Ruttenberg]

Is the intention that terms such as 'White matter of diencephalon' refer to a single thing which is the sum of all white matter that is part of the diencephalon, or is it the intention that it be the type of any little piece of white matter that is part of the diencephalon. 

The documentation for white matter of the neuraxis suggests the second interpretation.

OM: 1. gray matter is a cluster of neural somas while white matter is a cluster of neurites (axons and/or dendrites). In both cases, it's a collection of cell parts plus intervening connective tissue and vasculature. n2. this is a semantic class; it does not represent the entire white matter as one whole unit.

However a couple of things struck me. "

1) In the definition of the forebrain white and gray matter are constitutional parts

'Forebrain' :IS-A 'Cardinal segment of brain'

  'constitutional part' 'Gray matter of forebrain')

  'constitutional part' 'White matter of forebrain')

  'regional part' 'Diencephalon')

  'regional part' 'Telencephalon')

  'definition' "Organ component of neuraxis that has as its parts the

    telencephalon, diencephalon, lateral ventricles and third

    ventricle. Examples: There is only one forebrain."))

2) It seems clear that *some* subclasses are intended to be sums

'Gray matter of left hippocampus proper' :IS-A 'Gray matter of hippocampus proper'... 'Gray matter of neuraxis'

  'constitutional part of' 'Left hippocampus proper'

  'constitutional part' 'Ependyma of left hippocampus proper'

  'constitutional part' 'Pyramidal layer of left hippocampus proper'

  'constitutional part' 'Radiate layer of left hippocampus proper'

  'constitutional part' 'Oriens layer of left hippocampus proper'

  'constitutional part' 'Lacunar-molecular layer of left hippocampus proper'

3) It looked a little odd that e.g. White matter of thalamus has part Neuroglial network of white matter of diencephalon. But this is just going on names.

 

'White matter of diencephalon' :IS-A 'White matter of neuraxis'

  'constitutional part of' 'Diencephalon'

  'constitutional part' 'Neuroglial network of white matter of diencephalon'

  'constitutional part of' 'Neural tissue of diencephalon'

  :SUBCLASSES ('White matter of subthalamus'

               'White matter of epithalamus'

               'White matter of thalamus'

               'White matter of hypothalamus'

               'Capsule of diencephalon')

In general there seems to be a few hierarchies that parallel some amount of the part structure of the brain and I'm having some trouble keeping track of the purpose of it all - there's the White/gray matter of xxx, Set of xxx, Segment of xxx, Neural tissue of xxx, ....

-Alan

[Barry Smith]

Looks like it should be 'portion of gray matter (etc.)' to me
BS

[mej...@comcast.net]

Same issue as in gray matter and I agree this needs to be cleaned up.

Response in-line below.

OM

----- Original Message -----
From: "Alan Ruttenberg" <alanrut...@gmail.com>
To: "fma-owl-2009" <fma-ow...@googlegroups.com>
Sent: Friday, June 11, 2010 3:58:27 AM GMT -08:00 US/Canada Pacific
Subject: white matter/gray matter

Is the intention that terms such as 'White matter of diencephalon' refer to a single thing which is the sum of all white matter that is part of the diencephalon, or is it the intention that it be the type of any little piece of white matter that is part of the diencephalon. 

The documentation for white matter of the neuraxis suggests the second interpretation.

OM: 1. gray matter is a cluster of neural somas while white matter is a cluster of neurites (axons and/or dendrites). In both cases, it's a collection of cell parts plus intervening connective tissue and vasculature. n2. this is a semantic class; it does not represent the entire white matter as one whole unit.

However a couple of things struck me. "

1) In the definition of the forebrain white and gray matter are constitutional parts

'Forebrain' :IS-A 'Cardinal segment of brain'

  'constitutional part' 'Gray matter of forebrain')

  'constitutional part' 'White matter of forebrain')

  'regional part' 'Diencephalon')

  'regional part' 'Telencephalon')

  'definition' "Organ component of neuraxis that has as its parts the

    telencephalon, diencephalon, lateral ventricles and third

    ventricle. Examples: There is only one forebrain."))

OM:
The definition needs to be updated to:
"Cardinal segment of brain which has as its direct parts telencephalon, diencephalon, right lateral ventricle, left lateral ventricle and third ventricle. Examples: There is only one forebrain."

In this case, gray matter of forebrain is a semantic class, not a single entity. Therefore it should have subclasses such as cerebral cortex, basal ganglia nuclei, thalamic complex, etc.
The constitutional part therefore should be "set of gray matter structures of forebrain", with members such as cerebral cortex, basal ganglia nuclei, thalamic complex, etc.
Same story for the white matter parts.

2) It seems clear that *some* subclasses are intended to be sums

'Gray matter of left hippocampus proper' :IS-A 'Gray matter of hippocampus proper'... 'Gray matter of neuraxis'

  'constitutional part of' 'Left hippocampus proper'

  'constitutional part' 'Ependyma of left hippocampus proper'

  'constitutional part' 'Pyramidal layer of left hippocampus proper'

  'constitutional part' 'Radiate layer of left hippocampus proper'

  'constitutional part' 'Oriens layer of left hippocampus proper'

  'constitutional part' 'Lacunar-molecular layer of left hippocampus proper'

3) It looked a little odd that e.g. White matter of thalamus has part Neuroglial network of white matter of diencephalon. But this is just going on names.

OM: This relationship is not in my copy of the FMA.

 

'White matter of diencephalon' :IS-A 'White matter of neuraxis'

  'constitutional part of' 'Diencephalon'

OM: not valid anymore, see above. Should now be "set of white matter structures of diencephalon".

  'constitutional part' 'Neuroglial network of white matter of diencephalon'

OM: The FMA follows the "splitter" approach (as opposed to lumpers) where the white matter actually consists of a set of neurites, a network of glial cells and a vascular network. Data entry has not yet been completed here.

  'constitutional part of' 'Neural tissue of diencephalon'

OM: "Neural tissue of diencephalon" may not be appropriate. Remember  tissue is defined as "consisting of cells, not cell parts".  So this term may not be valid. Perhaps "neural cluster of diencephalon" is the correct term to represent the structure.

  :SUBCLASSES ('White matter of subthalamus'

               'White matter of epithalamus'

               'White matter of thalamus'

               'White matter of hypothalamus'

               'Capsule of diencephalon')
OM: The above white matter structures are correctly assigned as subclasses of "White matter of diencephalon"

In general there seems to be a few hierarchies that parallel some amount of the part structure of the brain and I'm having some trouble keeping track of the purpose of it all - there's the White/gray matter of xxx, Set of xxx, Segment of xxx, Neural tissue of xxx, ....

OM:
I understand the confusion. The brain is unlike the rest of the body where some rules are not followed and so we have to come up with new schemes and nomenclature to accommodate neural structures while being consistent with the rules we set or declare for the rest of the body. Again remember that I have not completed the review of the entire neuroanatomy component of the FMA and as you can imagine, it is a daunting task, especially now that I know that consensus is really not there for many structures. However you will realize that the framework can accommodate and even reconcile all kinds of parcellations. Here are a few points or guides to help you, some of them I mentioned already:
1. Gray matter and white matter are not tissues.
2. Nuclei as gray matter structures are treated as anatomical sets.
3. The term "segment" is used to describe partitions using fiat boundaries based on some defined anatomical landmark(s).
4. The term "zone" is used to describe partitions using fiat boundaries NOT based on some defined anatomical landmark(s), purely man-made arbitrary decision.
5. The term "subdivision" is an old term used to describe both segments and zones and will need to be updated soon.
6. When dealing with tissue, there is a predominant group which is supported or accompanied by a minor group. Neural tissue means it consists predominantly of a collection of neurons but also consists of supportive cells (glial cells) as well as a vascular network. The same is true for other tissues such as the muscle tissue (myocytes + vascular and neural networks + connective tissue [e.g. endomysium, perimysium]).

If I think of any more that can be helpful I'll send them right away. Anyway, all your questions are extremely helpful to me and it brings my attention to areas that are in desperate need of edits and updates. Many thanks!

Onard

[Alan Ruttenberg]

On Fri, Jun 11, 2010 at 10:43 PM, <mej...@comcast.net> wrote:
> 3) It looked a little odd that e.g. White matter of thalamus has
> part Neuroglial network of white matter of diencephalon. But this is just
> going on names.
>
> OM: This relationship is not in my copy of the FMA

It's implied, since every White matter of thalamus is a White matter
of neuraxis and every White matter of neuraxis has a constitutional

part Neuroglial network of white matter of diencephalon

'White matter of diencephalon' :IS-A 'White matter of neuraxis'
'constitutional part of' 'Diencephalon'

'constitutional part' 'Neuroglial network of white matter of diencephalon'

'constitutional part of' 'Neural tissue of diencephalon'

:SUBCLASSES

'White matter of subthalamus'
'White matter of epithalamus'
'White matter of thalamus'
'White matter of hypothalamus'
'Capsule of diencephalon'

-Alan