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BIO303: Neurobiology

Unit 5: Neural Development   *The nervous system, elaborate and complicated as it is, developed from a single cell. This unit will cover the major concepts behind the remarkable process of neural development. This unit’s information draws heavily from the developmental biology course; if you are interested in development, you should consider enrolling in that course as well. 

You will learn that the growth process begins with neurulation and neural tube formation and continues along a very fast path. It involves a huge number of different types of cells and signals but we will cover only those that have the most significant impact. Finally, we will examine some birth defects that arise from improper development.*

Unit 5 Time Advisory
This unit will take you 10.5 hours to complete.

☐    Subunit 5.1: 2.5 hours

☐    Subunit 5.2: 1.5 hours

☐    Subunit 5.3: 1.5 hours

☐    Subunit 5.4: 3 hours

☐    Subunit 5.5: 2 hours

Unit5 Learning Outcomes
Upon successful completion of this unit, the student will be able to:
- explain the steps of gastrulation and neurulation; - explain how retinoic acid, growth factors, BMPs, and sonic hedgehog function to properly form the nervous system; - explain the general organization of the spinal cord, and the internal organization of the spinal cord; and - explain the causes and impacts of the altered development syndromes, Fragile X, hydrocephalus, autism, and Down’s Syndrome.

5.1 Gastrulation and Neurulation   5.1.1 Notochord   - Reading: Kenyon College: Life – The Science of Biology 6th Ed.: “Chapter 14: Gastrulation and Neurulation” Link: Kenyon College: Life – The Science of Biology 6th Ed.: ** “Chapter 14: Gastrulation and Neurulation (HTML and Quicktime)
 
Instructions: Read the sections on “Gastrulation,” “Gastrulation in Birds and Mammals,” and “Neurulation.”
 
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5.1.2 Primitive Streak and Pit   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 22: The Initial Formation of the Nervous System: Gastrulation and Neurulation” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 22: The Initial Formation of the Nervous System: Gastrulation and Neurulation” (HTML)
 
Instructions: Read the entire webpage.
 
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5.1.3 Retinoic Acid   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Box A – Retinoic Acid: Teratogen and Induction Signal” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Box A – Retinoic Acid: Teratogen and Induction Signal” (HTML)
 
Instructions: Read the entire webpage, and carefully view the images. Vitamin A is essential for the normal development of vertebrate embryos. If a developing embryo is deprived of vitamin A, the fetus, particularly the fetal brain, will not form correctly. Vitamin A itself is not directly responsible for the regulation of embryonic development. Vitamin A is metabolized to form RETINOIC ACID. Retinoic acid is essential in determining position along the embryonic anterior/posterior axis and the dorsal/ventral axis. The biological importance of retinoic acid has long been known, as major developmental abnormalities follow retinoic acid deprivation or exposure to excess retinoic acid. Some of these abnormalities resemble congenital birth defects that are relatively common in humans, including spina bifida and cleft palate.
 
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5.1.4 Growth Factors, Bone Morphogenetic Proteins (BMPs), and Sonic Hedgehog (Shh)   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 22: The Molecular Basis of Neural Induction” Link: NCBI Bookshelf’sversion of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 22: The Molecular Basis of Neural Induction (HTML)
 
Instructions: Read the entire webpage. Note that you have already reviewed Box A in the previous subunit 5.1.3. You may want to spend some time re-reviewing this figure. Make sure to also click on the link to and explore Figure 22.3.
 
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5.2 Major Subdivision   5.3 Major Subdivision   5.3.1 Prosencephalon   - Reading: The University of Texas’s Neuroscience Online: Dr. Dafny’s “Ch 1: Overview of the Nervous System” Link: The University of Texas’s Neuroscience Online: Dr. Dafny’s “Ch 1: Overview of the Nervous System” (HTML)
 
Instructions: Read Chapter 1. This reading also covers subunits 5.2.2 and 5.2.3.
 
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5.3.2 Mesencephalon   Note: This topic is covered by the reading under subunit 5.2.1.

5.3.3 Rhombencephalon   Note: This topic is covered by the reading under subunit 5.2.1.

5.3.4 Spinal Cord   - Reading: The University of Texas’s Neuroscience Online: Dr. Nachum Dafny’s “Ch 3: Anatomy of the Spinal Cord” Link: The University of Texas’s Neuroscience Online: Dr. Nachum Dafny’s “Ch 3: Anatomy of the Spinal Cord” (HTML)
 
Instructions: Read all 4 pages of the chapter.
 
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  • Reading: Temple University’s Neuroanatomy Lab Resource Appendices: “Neuroembryology” Link: Temple University’s Neuroanatomy Lab Resource Appendices: “Neuroembryology (HTML)
     
    Instructions: Read both pages of this link. Make sure to click on the hyperlink labeled “Click here to move on to the next page” to move on to the second page of the article.
     
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5.3.5 Homeotic Genes   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Box B – Homeotic Genes and Human Brain Development” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Box B – Homeotic Genes and Human Brain Development” (HTML)
 
Instructions: Read the entire webpage.
 
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5.3.6 Rhombomeres   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Box C – Rhombomeres” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Box C – Rhombomeres” (HTML)
 
Instructions: Read the entire webpage, and view the images carefully.
 
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5.4 Neuronal Differentiation   5.4.1 Neurogenesis   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 22: The Initial Differentiation of Neurons and Glia” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 22: The Initial Differentiation of Neurons and Glia” (HTML)
 
Instructions: Read the entire webpage, and click on the hyperlinks to read Box D, Figure 22.6, and Figure 22.7.
 
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5.4.2 Neural Crest Cells   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 22: The Initial Formation of the Nervous System: Gastrulation and Neurulation” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 22: The Initial Formation of the Nervous System: Gastrulation and Neurulation” (HTML)
 
Instructions: You have read this website in Subunit 5.1.2, but to focus on neural crest cells, please read the third paragraph, and click on the hyperlink to Figure 22.2.
 
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5.5 Neural Circuit Formation   5.5.1 Axonal Growth Cone   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 23: The Axonal Growth Cone” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 23: The Axonal Growth Cone” (HTML)
 
Instructions: Read the entire webpage, and click on the hyperlinks to the figures.
 
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5.5.2 Chemoattraction and Repulsion   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 23: Diffusible Signals for Axon Guidance: Chemoattraction and Repulsion” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 23: Diffusible Signals for Axon Guidance: Chemoattraction and Repulsion” (HTML)
 
Instructions: Read the entire webpage, and click on the hyperlinks to the figures.
 
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5.5.3 Topographic Maps and Chemoaffinity Hypothesis   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 23: The Formation of Topographic Maps” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 23: The Formation of Topographic Maps” (HTML)
 
Instructions: Read the entire webpage, and click on the hyperlinks to the figures.
 
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5.5.4 Neurotrophic Factors   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 23: Trophic Interactions and the Ultimate Size of Neuronal Populations” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 23: Trophic Interactions and the Ultimate Size of Neuronal Populations” (HTML)
 
Instructions: Read the entire webpage, and click on the hyperlinks to the figures.
 
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5.5.5 Selective Synapse Formation   - Reading: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 23: Selective Synapse Formation” Link: NCBI Bookshelf’s version of Sinauer Associates, Inc., Purves, Augustine, Fitzpatrick, et al., editors’ Neuroscience, 2nd Edition: “Ch 23: Selective Synapse Formation” (HTML)
 
Instructions: Read the entire webpage, and click on the hyperlinks to the figures.
 
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5.6 Altered Development   5.6.1 Fragile-X Syndrome   - Reading: The National Fragile-X Foundation: “Fragile X-associated Disorders” Link: The National Fragile-X Foundation: “Fragile X-associated Disorders (HTML)
                                      
Instructions: Read the entire webpage and click on the links to Fragile X syndrome, and Fragile X-associated Tremor/Ataxia Syndrome. Note that you are not required to fill out any information for the free brochure.
 
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5.6.2 Hydrocephalus   - Reading: National Institute of Neurological Disorder and Stroke: “Hydrocephalus Fact Sheet” Link: National Institute of Neurological Disorder and Stroke: “Hydrocephalus Fact Sheet” (HTML)
 
Instructions: Read the entire webpage.
 
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5.6.3 Autism   - Reading: National Institute of Neurological Disorder and Stroke: “Autism Fact Sheet” Link: National Institute of Neurological Disorder and Stroke: “Autism Fact Sheet” (HTML)
 
Instructions: Read the entire webpage.
 
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5.6.4 Trisomy 21 (Down Syndrome)   - Reading: National Association for Down Syndrome: “Facts About Down Syndrome” Link: National Association for Down Syndrome: “Facts About Down Syndrome” (HTML)
 
Instructions: Read the entire webpage.
 
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  • Assessment: The Saylor Foundation’s “Unit 5 Assessment” Link: The Saylor Foundation’s “Unit 5 Assessment (PDF)

    Instructions: Complete this quiz after working through Unit 5. The questions are either multiple choice, matching, or labeling diagrams. Your answers can be checked against The Saylor Foundation’s Unit 5 Assessment Answer Key (PDF).

    Completing this assessment should take approximately 30 minutes.