Embryological Subdivisions of the Human CNS

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Из курса от партнера Duke University

Medical Neuroscience

1042 оценки

Duke University

Medical Neuroscience

1042 оценки

Medical Neuroscience explores the functional organization and neurophysiology of the human central nervous system, while providing a neurobiological framework for understanding human behavior. In this course, you will discover the organization of the neural systems in the brain and spinal cord that mediate sensation, motivate bodily action, and integrate sensorimotor signals with memory, emotion and related faculties of cognition. The overall goal of this course is to provide the foundation for understanding the impairments of sensation, action and cognition that accompany injury, disease or dysfunction in the central nervous system. The course will build upon knowledge acquired through prior studies of cell and molecular biology, general physiology and human anatomy, as we focus primarily on the central nervous system. This online course is designed to include all of the core concepts in neurophysiology and clinical neuroanatomy that would be presented in most first-year neuroscience courses in schools of medicine. However, there are some topics (e.g., biological psychiatry) and several learning experiences (e.g., hands-on brain dissection) that we provide in the corresponding course offered in the Duke University School of Medicine on campus that we are not attempting to reproduce in Medical Neuroscience online. Nevertheless, our aim is to faithfully present in scope and rigor a medical school caliber course experience. This course comprises six units of content organized into 12 weeks, with an additional week for a comprehensive final exam: - Unit 1 Neuroanatomy (weeks 1-2). This unit covers the surface anatomy of the human brain, its internal structure, and the overall organization of sensory and motor systems in the brainstem and spinal cord. - Unit 2 Neural signaling (weeks 3-4). This unit addresses the fundamental mechanisms of neuronal excitability, signal generation and propagation, synaptic transmission, post synaptic mechanisms of signal integration, and neural plasticity. - Unit 3 Sensory systems (weeks 5-7). Here, you will learn the overall organization and function of the sensory systems that contribute to our sense of self relative to the world around us: somatic sensory systems, proprioception, vision, audition, and balance senses. - Unit 4 Motor systems (weeks 8-9). In this unit, we will examine the organization and function of the brain and spinal mechanisms that govern bodily movement. - Unit 5 Brain Development (week 10). Next, we turn our attention to the neurobiological mechanisms for building the nervous system in embryonic development and in early postnatal life; we will also consider how the brain changes across the lifespan. - Unit 6 Cognition (weeks 11-12). The course concludes with a survey of the association systems of the cerebral hemispheres, with an emphasis on cortical networks that integrate perception, memory and emotion in organizing behavior and planning for the future; we will also consider brain systems for maintaining homeostasis and regulating brain state.

Из урока

The Changing Brain: The Brain Across the Lifespan

This module represents another turning point in Medical Neuroscience. Now that we have surveyed human neuroanatomy and our sensory and motor systems, we are ready to take a step back and consider how this magnificent central nervous system came to be the way that it is. We will also learn how the brain re-wires itself across the lifespan as genetic specification, experience-dependent plasticity and self-organization continue to interact, re-shaping the structure and function of neural circuits throughout the central nervous system.

Embryological Subdivisions of the Human CNS8:47

Major Forces In Early Brain Development12:36

Neurulation11:17

Formation of the Early CNS12:35

Inductive Signaling In CNS Formation15:10

Proliferation and Migration, part 117:23

Proliferation and Migration, part 210:59

Growth Cones11:42

Molecular Signals for Axon Guidance, part 113:22

Molecular Signals for Axon Guidance, part 212:36

Neurotrophins13:08

Neurotrophin Receptors and Synapse Formation11:43

Познакомьтесь с преподавателями

Leonard E. White, Ph.D.
Associate Professor
Department of Neurology, Department of Neurobiology, Duke University School of Medicine; Department of Psychology & Neuroscience, Trinity College of Arts & Sciences; Director of Education, Duke Institute for Brain Sciences; Duke University

Hello everyone. Welcome to this tutorial on the

embryological subdivisions of the human central nervous system.

This tutorial pertains to our first core concept in the field of neuroscience:

that the brain is the body's most complex organ.

Although given the brevity and the, relative simplicity of today's tutorial,

as well as your progress in the course thus far the complexity of the human

brain won't exactly be front and center in our consideration.

Really, what I'd like for you to be able to accomplish in this tutorial, is to

really refresh your appreciation and your understanding of the basic parts of the

adult form of the human brain. And so doing, what I want you to be able

to do is to identify each of the major subdivisions of the adult nervous system.

But now I want you to be able to relate them back to the embryological precursors

and associated ventricular spaces. Well, after all we're entering unit 5 of

medical neuroscience and our goal is to understand the changing brain.

And that story, of course begins in embryological life.

With the first formation of the central nervous system that occurs, really,

beginning in about the third week of the gestation of human life.

And ultimately what we want to be able to do is understand, where did this

marvelous form come from in the process of building the human organism.

Well, I hope to simply review some of the parts that we see in the adult human

brain with you in this session, and relate them back to the terminology that

we used to describe the developing brain in embryological life.

So this will be largely review. And I hope that you'll appreciate this

bit of a pivot as we turn from our studies of the adult form, to a

consideration of the mechanisms that are responsible for building the human brain,

the body's most complex organ. So, we will return to the lab, and have a

chance to once again, review the anatomy of an actual human brain specimen.

So I'll see you there. The lab lesson today is to recognize the

embryological forms that are viewable in the adult brain.

So let me reach into my bin and get a whole adult brain specimen.

So when we look at the brain in its adult form, it's really amazing to think that

this structure in front of me is derived from a simple tube.

But as we just learned at about the third week of gestation the nervous system is

in fact a simple tube, and that tube begins to form, a very prominent bulge in

the front part and then two smaller bulges, one in the middle and one towards

the back. And what we're looking at in front of us

is mostly what has become of that forward bulge in that tube.

And this is the cerebral hemispheres. This is the left hemisphere.

This is the right. So that forward bulge divides into two

parts. So most of what we see when we look at

the adult brain is, in fact, this forward bulge.

And we call this the Prosencephalon. Or forebrain, for short.

Pro meaning fore, and encephalon meaning brain.

So now we're looking at the posterior or the back side of the brain.

And we can see a portion of the hind brain, or the rhombencephalon.

And the major structure that's visible here is called the cerebellum.

The cerebellum is a large part of the brain which expands into two prominent

hemispheres, a left hemisphere and a right hemisphere.

And then if I just pick the brain up just a small amount, we can see the additional

part of the hind brain that's visible from the posterior surface, and that is

the brain stem. But to get a really get a good look at

the hindbrain, the rhombencephalon, we need to look at the ventral surface of

the brain. So now we're looking at the underside or

the ventral surface of the brain. And we'll have another lab lesson on many

of the features that we see. For today I want to focus on the

embryological divisions. So again all of these cerebral cortex

that we see in the hemispheres this is part of the forebrain or the

prosencephalon. Now on the ventral side, we can see a

small division of the prosencephalon that form structures that we call in the adult

form the thalamus and the hypothalamus. Together this is called the diencephalon,

and we can see that, just behind this optic nerve and its crossing, there is a

surface of the diencephalon here. That is the hypothalamus.

And I believe we can see these two small bulges.

These are called the mammillary bodies, and that is one surface landmark that

tells us that we're looking at the floor of the diencephalon.

The mammillary bodies being part of the hypothalamus.

Well, just behind the mammillary bodies, we see, the midbrain.

And from this view what we can see are two broad columns.

These are called the cerebral peduncles. Peduncle is a word that means stalk, and

these are two broad stalks that seem to support the cerebral hemispheres.

That's the midbrain. Now just below the cerebral peduncle is

this broad surface here, this is called the Pons.

The Pons is that part of the hindbrain that is intimately connected to the

cerebellum. In fact, I think you can appreciate how

the pons seems to stream out laterally right into the cerebellum on either side.

So that's the pons, together with the cerebellum, this is called the

Metencephalon, which is a sub-division of the hind-brain.

And then finally, just below the pons, is a complex part of the brain stem called

the medulla oblongata, or just the medulla for short.

And the medulla is that part of the brain stem that connects to the spinal cord.

Now, from a different specimen, I'd like to show you what the human spinal cord

looks like, and it would attach to this cut surface of the medulla.

Now, attached to the bottom of the brain stem, of course, is the spinal cord.

And I have several segments of spinal cord to show you.

This is the upper third of the spinal cord that attaches to the bottom of the

brain at the brain stem, but this has been removed so I'll go ahead and set

this brain down and we'll turn our attention to the spinal cord.

This is the upper third, which includes the cervical enlargement.

And then this is the middle third of the spinal cord that is the part that's in

the region of the thorax. We call that, the thoracic spinal cord.

And then down below, is the lumbosacral enlargement.

The cervical enlargement is concerned mainly with our arms and our hands.

And the lumbar enlargement is concerned mainly with our legs and our feet.

And just below the lumbar enlargement is the most inferior segment of the spinal

cord and its called the cauda equina. And as we get a close look at the cauda

equina you can see why it has its name. Couda equina means horses tail.

And what we see is the terminus of the spinal cord with a set of spinal nerves

that extend for several vertebral segments out from the vertebral column to

serve the lower part of the body.

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