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Chapter 9

PSY290H1 Chapter Notes - Chapter 9: Frontal Lobe, Monocular Deprivation, Dentate Gyrus

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Junchul Kim

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Chapter 9 Development of the Nervous System
3 ideas of neuro development:
1. The amazing nature of neurodevelopment
2. The important role of experience in neurodevelopment
3. The dire consequences of neurodevelopmental errors
Two devastating disorders: Autism and Williams disorder
9.1 Phases of Neurodevelopment
Started with a zygote, the cell thats formed by amalgamation of an ovum and a
3 things cell multiplication must occur:
1. Cells must differentiate
2. Cells must make their way to appropriate sites and align themselves with the
cells around them to form particular structures
3. Cells must establish appropriate functional relations with other cells
5 phases of neuro-development:
1. Induction of the neural plate
2. Neural proliferation
3. Migration and aggression
4. Axon growth and synapse formation
5. Neuron death and synapse rearrangement
Induction of the Neural Plate
Neuro Plate: a small patch of ectodermal tissue on the dorsal surface of the
developing embryo
The development of the neural plate is the first major stage of
neurodevelopment in all vertebrates
Mesoderm Layer: An area that is consequently referred to as an organizer,
which seems to induce the development of the neural plate by chemical signals
Totipotent: The earliest cells of the human embryo which have the ability to
develop into any type of cell in the body.
Multipotent: The cells of the early neural plate that have ability to develop
into most types of mature nervous system cell, but cannot normally develop into
other kinds of cells
Stem Cells: cells that meet two specific criteria:
1. Seemingly unlimited capacity for self-renewal if maintained in an
appropriate cell culture
2. Have the ability to develop into different types of mature cells
Stem cells have unlimited capacity for self-renewal because when a stem cell
divides, two different daughter cells are created, one that eventually develops
into some type of body cell and one that develops into another stem cell
Neural plate Neural Groove Neural Tube Cerebral ventricles and
Spinal canal (after 40 days, the three swellings develop into forebrain, midbrain
and hindbrain.)
Neural Proliferation

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Neural Proliferation: the process thats done by the cells of the neural tube
once its created and fused by the lips of the neural groove
It does not occur simultaneously or equally in all parts of the tube
Ventricular Zone: where the most cell division in the neural tube occur, which
is the region adjacent to the ventricle (the fluid-filled center of the tube)
Two organizer areas in the neural tube that control the pattern of
proliferation: the floor plate (runs along the midline of the anterior surface of
the tube) and the roof plate (runs along the midline of the dorsal surface of the
Migration and Aggregation
Migration: The procedure of cells movements once they have been
created through cell division in the ventricular zone of the neural tube; the
cells havent developed axons and dendrites at this stage
2 kinds of migrations:
Radial Migration: Cell proceeds from the ventricular zone in a
straight line outward toward the outer wall of the tube
Tangential Migration: Cell proceeds at a right angle to radial
migration (parallel to the tubes walls)
2 methods to develop cells migrate:
Somal Translocation: Extension grows from the developing cell in the
general direction of the migration, which explores the immediate
environment for attractive and repulsive cues as it grows
Glia-mediated Migration: Once the neural proliferation is well
underway and the walls of the neural tube are thickening, a
temporary network of glial cells (radial glial cells), appears in the
developing neural tube which let the cells engaging in radial
migration by moving along the radial glial network.
Inside-out pattern: the radial pattern of cortical development
Neural Crest: the structure that is situated just dorsal to the neural tube,
which develop into neurons and glial cells of the PNS (therefore, most of
them have to do a long-distance migration)
Many guidance molecules (the chemicals that guide the migrating
neurons by attracting or repelling) are released by glial cells.
Aggregation: the process about how neurons align themselves with other
developing neurons that have migrated to the same area to form the
structures of the nervous system
Cell-adhesion molecules (CAMs): What mediate migration and
aggregation, which are located on the surfaces of neurons and other cells
CAMs are critical to normal function and development of the brain
Gap junctions are also prevalent in brain development; which plays a role
in migration and aggregation as well.
Axon Growth and Synapse Formation
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