PSYC101 Lecture Notes - Thalamus, Peripheral Nervous System, Motor Cortex

44 views6 pages
30 Jan 2013
Department
Course

For unlimited access to Class Notes, a Class+ subscription is required.

Understanding CNS Structure through Development
The entire CNS is derived from the walls of a fluid-filled tube that is formed at an early stage in
embryonic development
o The tube becomes the adult ventricular system
Read Table 7.1 and 7.2
Formation of the Neural Tube
o Embryo begins as a flat disk with three distinct layers of cells called the endoderm,
mesoderm and the ectoderm
The endoderm gives rise to the lining of many of the internal organs (viscera)
The mesoderm arise the bones of the skeleton and the muscles
The nervous system and the skin derive entirely from the ectoderm
The ectoderm gives rise to the nervous system: the neural plate
o At about 17 days from conception (in humans), the brain consists only of a flat sheet of
cells.
Next is the formation of a grove in the neural plate that runs rostral to caudal
neural groove
The walls of the groove are called the neural folds
o The move and fuse together to form the neural tube
o The entire nervous system develops from the walls of the neural
tube
As the neural folds come together, some neural ectoderm is pinched off
and comes to lie just lateral to the neural tube neural crest
o
o All neurons with cell bodies in the peripheral nervous system
derive from the neural crest
o The neural crest develops in close association with the underlying mesoderm
The mesoderm at this stage forms prominent bulges on either side of the neural
tube called somites
From these somites, 33 individual vertebrae of the spinal column and
the related skeletal muscles will develop
The nerves that innervate these skeletal muscles are called somatic
motor nerves
o The process by which the neural plate becomes the neural tube is called neurulation
Occurs very early in embryonic development (22 days after conception)
The Primary Brain Vesicles
o The process by which structures become more complex and functionally specialized
during development differentiation
o The first step in differentiation is the development (at the rostral end of the neural tube)
of the three swellings called the primary vesicles
o The entire brain derives from the three primary vesicles of the neural tube
The rostral most vesicle is called the prosencephalon the forebrain
Behind the prosencephalon lies the mesencephalon midbrain
Caudal to this is the rhombencephalon hindbrain
Connects with the caudal neural tube gives rise to the spinal cord
Differentiation of the Forebrain
Unlock document

This preview shows pages 1-2 of the document.
Unlock all 6 pages and 3 million more documents.

Already have an account? Log in
o The next important development occur in the forebrain
Secondary Vesicles sprout off on both sides of the prosencephalon.
The secondary vesicles are the optic vesicles and the telencephalic vesicles
The unpaired structures that remain after the secondary vesicles have
sprouted is called the diencephalon
Differentiation of the Telencephalon and Diencephalon
The telencephalic vesicles together form the telencephalon (endbrain)
It continues to develop in four ways:
o They grow posteriorly so that they lie over and lateral to the
diencephalon
o Another pair of vesicles sprout off the ventral surfaces of the
cerebral hemisphere giving rise to the olfactory bulbs
o The cells of the walls of the telencephalon divide and
differentiate into various structures
o White matter systems develop, carrying axons to and from the
neurons of the telencephalon
See Fig.7.13 on page 184
The fluid-filled spaces within the cerebral hemispheres are called lateral
ventricles
The space at the center of the diencephalon is called the third ventricle
o Whenever you see paired fluid-filled ventricles in a brain
section, you know that the tissue surrounding them is the
telencephalon
Neurons form two different types of gray matter form in the
telencephalon: the cerebral cortex and the basal telencephalon
The diencephalon differentiates into two structure: the thalamus and
the hypothalamus
The neurons of the developing forebrain extend axons to communicate
with other parts of the nervous system
o These axons bundle together to form three major white matter
systems: the cortical white matter, the corpus callosum and the
internal capsule
Cortical white matter contains all axons that run to and
from the neurons in the cerebral cortex
Is continuous with the internal capsule (links
the cortex with the brain stem (esp.
hypothalamus)
Corpus callosum is continuous with the cortical white
matter and forms an axonal bridge that links cortical
neurons of the two cerebral hemispheres
Forebrain Structure-Function Relationship
Is the seat of perceptions, conscious awareness, cognition and voluntary
action
Depends on extensive interconnections with the sensory and motor
neurons of the brain stem and spinal cord
Unlock document

This preview shows pages 1-2 of the document.
Unlock all 6 pages and 3 million more documents.

Already have an account? Log in

Get access

Grade+
$10 USD/m
Billed $120 USD annually
Homework Help
Class Notes
Textbook Notes
40 Verified Answers
Study Guides
1 Booster Class
Class+
$8 USD/m
Billed $96 USD annually
Homework Help
Class Notes
Textbook Notes
30 Verified Answers
Study Guides
1 Booster Class