2017 Group Project 1: Difference between revisions

From Embryology
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==Abnormalities associated with Cerebral Cortex Development==
==Abnormalities associated with Cerebral Cortex Development==
( Zainab )  
( Zainab )  
DRAFT:
https://www.youtube.com/watch?v=luXDQrmMoUU
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2992410/ <br>
<ref>Squier, W. and Jansen, A. (2010). Abnormal development of the human cerebral cortex. Journal of Anatomy, [online] 217(4), pp.312-323. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2992410/ [Accessed 23 Sep. 2017]. </ref>
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3547618/ <br>
<ref>Pang, T., Atefy, R. and Sheen, V. (2008). Malformations of Cortical Development. The Neurologist, [online] 14(3), pp.181-191. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3547618/ [Accessed 23 Sep. 2017]. </ref>
http://www.cell.com/neuron/fulltext/S0896-6273(00)80749-7?_returnURL=http%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0896627300807497%3Fshowall%3Dtrue
<ref>Christopher A, C. (2017). Genetic Malformations of the Human Cerebral Cortex. Neuron, [online] 23(1), pp.19 - 29. Available at: http://www.cell.com/neuron/fulltext/S0896-6273(00)80749-7?_returnURL=http%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0896627300807497%3Fshowall%3Dtrue [Accessed 23 Sep. 2017].</ref>
https://academic.oup.com/jnen/article/61/1/1/2916251
https://pdfs.semanticscholar.org/67ea/2ce13f57f4ddbfb7033b6bb1328a5dff7742.pdf
https://www.youtube.com/watch?v=l_nTggR7LTE
<ref>Mahfouz, M. (2015). Imaging of cortical formation disorders - DRE 4 - Prof. Dr Mamdouh Mahfouz. [video] Available at: https://www.youtube.com/watch?v=l_nTggR7LTE [Accessed 23 Sep. 2017].</ref>


===A) Disorders due to abnormal proliferation, growth or differentiation of neuroblasts ===
===A) Disorders due to abnormal proliferation, growth or differentiation of neuroblasts ===
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<big><big>'''2-Hemimegalencephaly'''</big></big>
<big><big>'''2-Hemimegalencephaly'''</big></big>
<gallery>
[[File:Hemimegalencephaly.png]]
 
</gallery>
A rare congenital disorder that also results from the abnormal proliferation of neuroblasts is Hemimegalencephaly. <br/>
A rare congenital disorder that also results from the abnormal proliferation of neuroblasts is Hemimegalencephaly. <br/>
'''Hemimegalencephaly''' is a developmental disorder which consists of a 'hamartomatous' overgrowth (where normal mature cells and tissues  normally present in an area of the body, form a tumour-like, benign malformation) on part of all of the cerebral hemisphere.  
'''Hemimegalencephaly''' is a developmental disorder which consists of a 'hamartomatous' overgrowth (where normal mature cells and tissues  normally present in an area of the body, form a tumour-like, benign malformation) on part of all of the cerebral hemisphere.  
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<html5media height="400" width="500">https://www.youtube.com/watch?v=7zOa3LLrHKc</html5media>
<html5media height="400" width="500">https://www.youtube.com/watch?v=7zOa3LLrHKc</html5media>
<ref>Ezzo - Izzo, D. (2007). How the Body Works : The Corpus Callosum. [video] Available at: https://www.youtube.com/watch?v=7zOa3LLrHKc [Accessed 23 Sep. 2017].</ref>
<ref>Ezzo - Izzo, D. (2007). How the Body Works : The Corpus Callosum. [video] Available at: https://www.youtube.com/watch?v=7zOa3LLrHKc [Accessed 23 Sep. 2017].</ref>
https://www.youtube.com/watch?v=luXDQrmMoUU
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2992410/ <br>
<ref>Squier, W. and Jansen, A. (2010). Abnormal development of the human cerebral cortex. Journal of Anatomy, [online] 217(4), pp.312-323. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2992410/ [Accessed 23 Sep. 2017]. </ref>
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3547618/ <br>
<ref>Pang, T., Atefy, R. and Sheen, V. (2008). Malformations of Cortical Development. The Neurologist, [online] 14(3), pp.181-191. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3547618/ [Accessed 23 Sep. 2017]. </ref>
http://www.cell.com/neuron/fulltext/S0896-6273(00)80749-7?_returnURL=http%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0896627300807497%3Fshowall%3Dtrue
<ref>Christopher A, C. (2017). Genetic Malformations of the Human Cerebral Cortex. Neuron, [online] 23(1), pp.19 - 29. Available at: http://www.cell.com/neuron/fulltext/S0896-6273(00)80749-7?_returnURL=http%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0896627300807497%3Fshowall%3Dtrue [Accessed 23 Sep. 2017].</ref>
https://academic.oup.com/jnen/article/61/1/1/2916251
https://pdfs.semanticscholar.org/67ea/2ce13f57f4ddbfb7033b6bb1328a5dff7742.pdf
https://www.youtube.com/watch?v=l_nTggR7LTE
<ref>Mahfouz, M. (2015). Imaging of cortical formation disorders - DRE 4 - Prof. Dr Mamdouh Mahfouz. [video] Available at: https://www.youtube.com/watch?v=l_nTggR7LTE [Accessed 23 Sep. 2017].</ref>


==INFO/ Research Links (temporary heading)==
==INFO/ Research Links (temporary heading)==

Revision as of 23:46, 4 October 2017

2017 Student Projects 
Student Projects: 1 Cerebral Cortex | 2 Kidney | 3 Heart | 4 Eye | 5 Lung | 6 Cerebellum
Student Page - here is the sample page I demonstrated with in the first labs.I remind all students that you have your own Group Forum on Moodle for your discussions, it is only accessible by members of your group.
Editing Links: Editing Basics | Images | Tables | Referencing | Journal Searches | Copyright | Font Colours | Virtual Slide Permalink | My Preferences | One Page Wiki Card | Printing | Movies | Language Translation | Student Movies | Using OpenOffice | Internet Browsers | Moodle | Navigation/Contribution | Term Link | Short URLs | 2018 Test Student

Cerebral Cortex

Mark Hill (talk) 15:59, 14 September 2017 (AEST) Feedback

  • lots of sub-headings, but no actual text.
  • no defined structure to the sequence of sub-headings.
  • no research images related to what is an extensively researched topic.
  • historic background of key research findings, put our understanding today in perspective.
  • Lon list of abnormalities, with no description.

Introduction

( Susannah )

What is it?

For concept: https://www.youtube.com/watch?v=dNngOlsLuGI

You might find this helpful (although you need to request copyright permission):

"Difference Between Cerebrum and Cerebral Cortex." DifferenceBetween.Com. August 7, 2012. < http://www.differencebetween.com/difference-between-cerebrum-and-vs-cerebral-cortex/ >

Histology of Cerebral Cortex

https://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0024757/ Z5177691 (talk) 22:37, 23 August 2017 (AEST)

Stage 22 image 217.jpg


Early Development of the Brain (and Nervous System)

( Eden )


https://www.youtube.com/watch?v=XdN9i_ZWGho

https://embryology.med.unsw.edu.au/embryology/index.php/Neural_-_Cerebrum_Development

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2989000/ https://embryology.med.unsw.edu.au/embryology/index.php/Neural_System_Development

Development of Cerebral Cortex

(z5177691)

Main classes of neurons [1]

  • Projection neurons: excitatory neurons (glutamatergic) with axons that project to distant targets and are generated by progenitors in the dorsal pallium of the telencephalon. The have a typical pyramidal structure and send signals to various regions of the brain and neocortex.
  • Interneurons: inhibitory neurons (GABAergic) that have local connections within the cortex and are generated in the subpallium of the telecephalon in the ventral proliferative zone. These neurons have to migrate to the neocortex area.


Key developmental zones in the human cortex:

  • Ventricular zone
  • Subventricular zone
    • Inner Subventricular Zone
    • Outer Subventricular zone
  • Intermediate Zone
  • Preplate: neural progenitor cells split into 2 regions
    • Marginal zone:
    • Subplate:
  • Cortical Plate: where the 6 layers of the cortex form, exists in between the subplate and the marginal zone

Timeline of Corticogenesis

The dorsolateral wall of the telencephalon is initially made up of undifferentiated neuroepithelial cells at the beginning of development. The cells are neural stem cells, capable of dividing into various neuronal subtypes. The timing of birth for these neuronal subtypes determines the location (e.g fate) of the neurons so that specific connections and cortical structure are achieved. "E" relates to embryonic day in relation to corticogenesis.

DAY DEVELOPMENT
E30 Progenitors in the dorsal telencephalon divide symmetrically and give rise to the initial ventricular zone (VZ), a single layer of cells that attach their "feet" to the cerebral wall and divide. These neurons lay adjacent to the ventricular surface. <pubmed> 18209730 </pubmed></ref>
E31-32 Dividing cells from the VZ begin to differentiate into "pioneer" neurons to form the preplate. These neurons migrate radially and tangentially from the VZ to the pial surface in an upward fashion. These cells are often referred to as radial glial cells (RGCs) because they contain radial fibers that span the entire embryonic wall from the VZ to the pial surface. These fibers create a "scaffolding" for subsequent migrating neurons to attach to and travel along in order to expand the neocortex. These cells are multipotent cells that divide asymmetrically to produce intermediate precursor cells that can become projection neurons, astrocytes, and oligodendrocytes [2] . The preplate is referred to as heterogeneous because it contains many developing cell types.
E40-45 Cells in the VZ continue to divide symmetrically and give rise to another zone known as the subventricular zone (SVZ). This proliferative layer lies above the ventricular zone and is not attached to the ventricular surface. Radial glial cells also populate this area as well as the preplate and many of the cells in the SVZ contribute to the later cortical neurons. The SVZ also separates into the outer subventricular zone (OSVZ) and the inner subventricular zone (ISVZ). The OSVZ continues to expand as it produces more migrating immature neurons and intermediate precursor cells (add #2 reference).
E50-55 The preplate begins to split into two subsections: the marginal zone and the subplate. An intermediate zone forms below the subplate and contains only migrating cells (migrating to the target destination) and no intermediate precursor cells. The cortical plate also begins to form in between the two regions. Newly born neurons that migrate to the cortical plate are developed "inside out". This term "inside-out" means that earlier born cells populate the deep layers first and later born neurons populate the superficial layers of the neocortex by migrating past the deep layers. Therefore, layers 6 is populated before layer 5; layer 5 is populated before layer 4 and so on. Each layer condenses and the neurons are closely packed. As the layers form, the cortex expands.

Migration and division of all six layers of the cortex is completed during the third trimester. Each layer has distinct synaptic connections and cell types that contribute to the specific functions of the cortex.

Cell Signaling

Anatomy of the Cerebral Cortex

( Jess)

You might find this helpful (although you need to request copyright permission): "Difference Between Cerebrum and Cerebral Cortex." DifferenceBetween.Com. August 7, 2012. < http://www.differencebetween.com/difference-between-cerebrum-and-vs-cerebral-cortex/ >

-layer grey matter outer surface of cerebrum

-2-4mm thickness

-most anterior (rostral) brain region

-outer zone of neuronal tissue (grey matter) containing neuronal cell bodies

-densely packed in humans with over 10 billion nerve cells (about 10% of all the neurons in the brain)

-where much of the neural activities of the cerebrum takes place

-divided left and right hemispheres by longitudinal fissure

-two hemispheres joined by corpus callosum at midline

-divided into functional areas that serve various sensory, motor and cognitive functions

-subdivisions of layers organizing input and output connectivity of resident neurons

-is folded in larger mammals to increase surface area, important allows addition and evolution of a greater diversity functional areas

-gyrus (gyri)= folds/ ridges

-sulcus (sulci)= groove

Layers

https://en.wikipedia.org/wiki/File:Gray754.png

Layer 1 -outer layer (pial surface)

-molecular layer, few scattered neurons

-mainly extensions of pyramidal neuron apical dentrite tufts

-some spiny stellate cells

-inputs to apical tufts crucial for feedback interactions in cortex in associative learning and attention

Layer 2 -external granular layer

-small pyramidal neurons

-many stellate neurons

Layer 3 -external pyramidal layer

-small and medium sized pyramidal neurons

-non-pyramidal neurons with vertically orientated intracortical axons

-layers 1, 2, 3 main target of interhemisphere corticocortical afferent fibres

-layer 3 main source of cortiocortical efferent fibres

Layer 4 -internal granular layer

-different types stellate and pyramidal neyrons

-main target thalamocortical afferents from thalamus type C neurons and intra-hemipsheric corticocortical afferents

Layer 5 -internal pyramidal layer

-large pyramidal neurons

-give rise to axons leaving cortex and run down to subcortical structures e.g. basal ganglia

-In primary motor cortex of the frontal lobe, this layer contains Betz cells and their axons travel through the internal capsule, the brain stem and the spinal cord forming the corticospinal tract

-which is the main pathway for voluntary motor control

Layer 6 -polymorphic/ multiform layer

-few large pyramidal neurons

-many small spindle like pyramidal and multiform neurons

-sends efferent fibers to thalamus forms exact reciprocal interconnection between thalamus and cortex

-connections are both inhibitory and excitatory

Other info three large surfaces: superolateral surface, medial surface, inferior surface

-surfaces characterised by sulci and gyri

three borders: superomedial border, inferomedial border, inferolateral border

lobes defined by large sulci (fissures)

named according to their relation to bones of skull

1) frontal lobe

2) parietal lobe

3) temporal lobe

4) occipital lobe


Blood Supply

Functions of the Cerebral Cortex

( Jess)

For concept:

https://www.youtube.com/watch?v=n6zQbTT0yoY

https://www.youtube.com/watch?v=X-m0JDCw6TE

Functional Areas

-Motor area (primary motor cortex)

-premotor area (motor association cortex)

-sensory area (pimary somatosensory cortex)

-auditory (acoustic) area

-olfactory area

-visual areas

-occipital eye field

-prefrontal areas (prefrontal cortex)

Abnormalities associated with Cerebral Cortex Development

( Zainab )

A) Disorders due to abnormal proliferation, growth or differentiation of neuroblasts

1-Focal cortical dysplasia (FCD)

In Focal Cortical Dysplasia, neurons are arranged abnormally in the focal areas of the cerebral cortex.
In all patients who present with seizures, FCD is the cause for about 5-15% of them.
FCD is of two types: Type I and Type II.

2-Hemimegalencephaly Hemimegalencephaly.png A rare congenital disorder that also results from the abnormal proliferation of neuroblasts is Hemimegalencephaly.
Hemimegalencephaly is a developmental disorder which consists of a 'hamartomatous' overgrowth (where normal mature cells and tissues normally present in an area of the body, form a tumour-like, benign malformation) on part of all of the cerebral hemisphere.

Hemimegalencephaly accounts for 0.2% of cases of childhood epilepsy. Clinical symptoms of this disease may include developmental delay, paralysis of one side of the body and blindness over half the field of vision; but the most significant symptom is seizures as 90% of patients present with this symptom.

3-Microcephaly

4-Tuberous Sclerosis

B) Disorders due to abnormal neuronal migration

5-Heterotopia

Migration of neurons occurs during the 8th week of development, along radial glial fibers (RGF).
RGFs can be damaged due to ischemia, which can be caused by infection resulting from trauma or metabolic errors.
RGF damage leads to the migration process arresting at the wrong time, resulting in abnormal or ectopic locations of neurons of the cortex.
This condition is known as Heterotopia.

There are different types of heterotopia:

  • Subcortical band heterotopia:

In this type of heterotopia, ectopic locations of neurons, seen as nodules, occur in the sub-cortical regions of the cerebral cortex.

  • Periventricular heterotopia/ sub-ependymal heterotopia:

In this type of heterotopia, ectopic locations of neurons, seen as nodules, occur in the sub-ependymal or periventricular area of gray matter of cerebral cortex.

  • Focal heterotopia:

In this type of heterotopia, abnormal location of neurons result in focal masses within deep white matter of cerebral cortex.

6-Lissencephaly

Lissencephaly is a congenital cortex malformation, in which gyri (and sulci) of the cerebral cortex are absent or largely absent, resulting in a smooth surface of the brain.

Lissencephaly is often characterised by the following features:

  • Total agyria (gyri and sulci absent resulting in 'smooth brain')
  • Pachygyria (gyri can be seen but are very few compared to normal brain)
  • Agyric brain with areas of pachygyria
  • Vertically oriented Sylvian fissures of the brain, giving the brain an 'hourglass' configuration

Lissencephaly has been associated with some other abnormalities as well, including corpus callosum hypoplasia, small brain stem and gray matter heterotopia.

Lissencephaly is further divided into types:

  • Classical (Type I) Lissencephaly- undermigration;
  • Cobblestone (Type II) lissencephaly- overmigration

Type II Lissencephaly also includes:

  1. Muscle-Eye-Brain Disease
  2. Walker-Warburg Syndrome
  3. Fragile X-Syndrome
  • Microlissencephaly


7-Kallmann Syndrome

C) Disorders due to abnormal cortical maturation and organization/folding

8-Polymicrogyria

If the neurons of the cerebral cortex successfully complete the proliferation and migration stages, but during the last organisation stage, distribute normally then multiple small undulating gyri can result.
This condition is called Polymicrogyria (PMG), in which, the gyri become extremely small (hence the term micro) and their number is greater than normal.
The cerebral cortex in this condition is flat and thickened, similar to that of pachygyria or agyria, and contains numerous small gyri.
Polymicrogyria is usually focal. It is most commonly 'perisylvian' (around the Sylvian fissure) followed by 'bilateral' and then 'unilateral'. The most common sites, in descending order, are the frontal lobe, parietal lobe, temporal lobe and then occipital lobe.

9-Schizencephaly

Schizencephaly is an organisational developmental disorder characterised by a cleft(s) or lesion(s) on the brain surface, which is filled with CSF and lined by gray matter.
Schizencephaly can be bilateral or unilateral.

The clefts can be small with closed walls in Type I or Closed lip type schizencephaly; or
the clefts can be large with free communication between the ventricle and subarachnoid spaces in Type II or Open lip type schizencephaly.

Schizencephaly commonly involves the parasylvian regions, and severity of the disease correlates with the extent of the clefts.

D) Others

12-Fetal Alcohol Spectrum Disorder (FASD)

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3670687/

13-Corpus Callosum Agenesis

<html5media height="400" width="500">https://www.youtube.com/watch?v=7zOa3LLrHKc</html5media> [3]


https://www.youtube.com/watch?v=luXDQrmMoUU

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2992410/
[4]

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3547618/
[5]

http://www.cell.com/neuron/fulltext/S0896-6273(00)80749-7?_returnURL=http%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0896627300807497%3Fshowall%3Dtrue [6]

https://academic.oup.com/jnen/article/61/1/1/2916251

https://pdfs.semanticscholar.org/67ea/2ce13f57f4ddbfb7033b6bb1328a5dff7742.pdf

https://www.youtube.com/watch?v=l_nTggR7LTE [7]

INFO/ Research Links (temporary heading)

PubMed Searches: Cerebral Cortex Development | Cerebrum Development

BMC Dev Biol Search: Cerebral Cortex Development

Recent papers

<pubmed limit=5>Cerebral+Cortex+Development</pubmed>

References

[Harvard Style]

  1. <pubmed> PMC3876965 </pubmed>
  2. <pubmed> PMC4334136 </pubmed>
  3. Ezzo - Izzo, D. (2007). How the Body Works : The Corpus Callosum. [video] Available at: https://www.youtube.com/watch?v=7zOa3LLrHKc [Accessed 23 Sep. 2017].
  4. Squier, W. and Jansen, A. (2010). Abnormal development of the human cerebral cortex. Journal of Anatomy, [online] 217(4), pp.312-323. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2992410/ [Accessed 23 Sep. 2017].
  5. Pang, T., Atefy, R. and Sheen, V. (2008). Malformations of Cortical Development. The Neurologist, [online] 14(3), pp.181-191. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3547618/ [Accessed 23 Sep. 2017].
  6. Christopher A, C. (2017). Genetic Malformations of the Human Cerebral Cortex. Neuron, [online] 23(1), pp.19 - 29. Available at: http://www.cell.com/neuron/fulltext/S0896-6273(00)80749-7?_returnURL=http%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0896627300807497%3Fshowall%3Dtrue [Accessed 23 Sep. 2017].
  7. Mahfouz, M. (2015). Imaging of cortical formation disorders - DRE 4 - Prof. Dr Mamdouh Mahfouz. [video] Available at: https://www.youtube.com/watch?v=l_nTggR7LTE [Accessed 23 Sep. 2017].