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.
Growth Cones
Loading...
Duke University 提供のコース
Medical Neuroscience
1265件の評価
レッスンから
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.
コースの提供者
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
Welcome back to this next tutorial in our series on the changing brain.
Today we're going to talk about the construction of neural circuits.
And this topic will pertain to three of our core concepts in the field of
neuroscience. Again, we're going to be talking about a
different kind of Neuronal communication communication that is mediated
chemically. But in this session, we're going to begin
to introduce the concept of building synaptic connections.
And that will enable both chemical and electrical communication to be possible
in developing neural circuits. So we're going to see the genesis of this
very important core concept in the field of neuroscience today as we consider the
construction of circuitry. We're going to talk about circuits that
are in large meder, measure genetically determined, circuits that provide the
foundation for behavior. such as the ability to detect potentially
painful and damaging stimuli in our skin surfaces.
And then lastly, we'll set the stage for a more rich discussion that I hope to
have with you in our next tutorial about how life experiences can modify the
structure and function of the central nervous system.
And I'd like to introduce a hypothesis really that will allow us to understand
how can chemical signals that have the ability to change the course of neural
development be modulated by activity? And this hypothesis will then help us
understand how life experience can change the structure and function of the brain.
Okay, well lets consider the learning objectives that I have for you in this
tutorial. I want you to be able to understand what
is a principal organelle that is responsible for pathfinding in developing
axons. As well as the, growth of dendritic
arbors. And this structure is called a growth
cone. So I want you to be able to characterize
the structure and function of growth cones.
I want you to be able to discuss the major classes of signaling molecules.
That guide axonal growth in the developing brain.
And I want you to be able to have a cogent discussion of neural trophins.
And I want you to be able to discuss the mechanisms of neural trophin signaling.
Well hopefully all of these topics will make sense to you after spending a little
time with me in this tutorial. So let's jump right into it.
Well, I would remind you of our broad framework for understanding the forces
that influence the developing brain. we talked, quite a bit in our last
tutorial about the concept of nature in brain development.
That is, the lineage-derived signals that result from the expression of particular
genes. And so this influence in brain
development can be considered genetic specification.
Well, today we're going to talk about the construction of neural circuits, which
begins to engage our two other major sets of factors that influence the finally
shape and structure and function of neural circuits.
Well, if indeed there is ever a final shape to them.
What I have in mind is self-organization. Self-organization is mediated via
activity based Mechanisms that play out as cells acquire the capacity to generate
electrical signals. And that begins to shape the expression
of a varierty of [UNKNOWN] types that circuits begin to acquire as they build
otu their connections. Well as the developing embryo, fetus, and
then to post natal life, developing infant begns to interact with the
environment. Then, sensory motor experience becomes an
important shaper of circuitry in an ongoing phase of circuit construction
that continues into post-natal life. So, the story of the construction of
neural circuits begins in utero. It begins at a, relatively, later stage
in embryonic development in the third trimester.
But it will continue, well into post natal life.
So many of the mechanisms we'll be talking about today reflect nature.
That is, genetic specification. However we will begin to describe some of
those factors that play an important role in mediating the influence of nurture.
And again that's going to be more primarily the topic of the next tutorial
in this series. Okay.
Well. With that as a broad introduction, let's
talk about some of these mechanisms that pertain to genetic specification and
self-organization in early brain development.
Mechanisms that will shape the growth and the viability of neurons and their
connections in the developing central nervous system.
Well the first set of mechanisms that play out establish polarity in the
developing neuroblast. Now, you'll recall that the neuroblast is
derived from epithelium and all epithelial cells acquire a polarity, that
is there's an epithelium, surface and a basal surface to their cells.
And, this process plays out in developing neuroblasts, although their apical and
basal surfaces are increasingly difficult to recognize, because increasingly these
cells no longer resemble the columnar epithelium that first established the
neuroectoderm. Nevertheless, theer os the establsihment
of polarity such that from the apical surface, of the developing neuroBlack, an
axon will emerge and from a basal surface, dendritic branches will begin to
grow out. Now initially, with the out growth of
these processes, we really can't. Tell whether they are destined to become
axon or dendrite, we simply call them neurites.
But as development progresses, a single axon becomes recognizable and
differentiated from the apical aspect of the neuroblasts, and that axon begins to
acquire a distinctive organelle. At the growing tip of that axon.
That's a structure that we call the growth cone.
Let's spend some time together thinking about the growth cone, and what makes it
such an important structure in the finding of axonal pathways in the
developing brain. Well, if one were to look at the tip of
an axon that is emerging let's say from a cell body somewhere in this direction.
One would find that there is a large, flattened structure that begins to
develop as that axon begins to differentiate from just a neurite that
might be extending away from this neuroblast.
So this structure, is what we call the growth cone.
And its charecterized by a fairly flat laminar type of appearance.
We call this a lamella podium or a sheet foot, that's one way to understand that
term. And then from that lamellipodium extend
these long finger like processes called filopodia.
Now what we're seeing in this figure is an illustration zooming in just on one
portion of the growth cone looking at a filopodia.
And this allows us to understand just a little bit about the dynamics that shape
this growth cone as it interacts with the environment of the developing embryo.
So what we find in this labella podium is a rich supply of mitochondria to supply
the energy that's necessary for the activity of the growth cone.
We also find a variety of filaments. We find actin filaments that assemble in
the philopodium, and this allows that philopodium to have a highly dynamic
behavior as actin polymers are assembled. From the monomeric elements.
So, the assembly of those filaments is responsible for the protusion of a
phyllopodium. And then the disassembly of those
filaments allows for the retraction of a phyllopodium.
Meanwhile, microtubules are being assembled and disassembled in the
lamellipodium. So, all of the machinery that's necessary
for the construction and deconstruction of these filaments, needs to be
synthesized and then localized to this growth cone.
Now, these processes are responding to signals in the environment through which
this growth cone is exploring. And those signals are tranduced via a
variety of receptors that are present within the leading edge of this growth
cone. So for example, one can find a variety of
channels, including our transcient receptor potential channels that can
mediate the interaction of this growth cone with chemical signals in the
environment. There are other means by which calcium
can enter this lamellipodium. And as you know calcium is a very
important second messenger system within all cells, and in particular within
developing neurons. So calcium becomes a key mediator of the
events that are detected at the plasma membrane of the growth cone which then
are transduced into changes in the structure and growth patterns of this
growth cone. So, this entire growth cone is a highly
modeled structure, so this growth cone can explore the environment.
Within which this axon might be proceeding.
It can decide that it needs to change directions.
Perhaps retract from growth in one direction, and begin to extend growth in
a different direction, perhaps an othoganal direction to the original
pattern of growth. So there is a tremendous amount of
dinamism associated with this growth cone as it actively explores the environment
responding to chemical signals. And sometimes there is an important point
of decision, is there not? There are what we might call forks in the
road. For a developing axon that's pioneering a
pathway. We think of these forks in a, in the road
in particular at the midline of the developing embryo.
Where a variety of exonal projections must make a choice.
To cross the midline or not to cross the midline.
Well, I thought this might be a helpful point to insert a study question to
challenge you to review some of what you know about anatomical pathways.
mainly those that you learned in unit 3 of the course.
So, let's just pause for a moment here, and take on the following study question.
コース一覧で検討
サインアップは無料です。今すぐサインアップして、パーソナライズされたお勧め、更新、サービスを利用しましょう。
コーセラは、世界トップクラスの教育を世界中に配信しています。
最高峰の大学や組織とのパートナーシップに基づくオンラインコースが提供されています。
© 2019 Coursera (株)すべての権利予約します。
