Nervous system development -
an introduction
Confidence Confident
Moment of
@February 12, 2024
lecture
Review @February 13, 2024
Lecture 1_NEURAL DEVELOPMENT ELLENDER
Materials
HANDOUT_240212_154818.pdf
Last Edited @March 12, 2025 9:36 AM
System neuroscience is at the intersection of neuroscience and systems
biology. You study the function of the neuronal circuit and it’s functions. We
zoom out in a way to look how cells work, how they form a neuronal network
and how these networks sustain a basis to basis to generate sensory
integration with cognition.
In the lecture series we will go from cellular to higher level cognition.
It is also important to know the different methods that are used as well as their
advantages and disadvantages. Here we want to have a combination of
research and education → therefore a lot of guest lectures are given. We need
to know the bigger picture and not specific papers.
Introduction
The aim of discussing brain development is that you look at different circuits in
the brain and how they arise (how do neurons wire in a certain way, etc).
Neurons connect with each other, in a very complex and extensive way (they
can be approximately 30 cm). Neurons wire up precisely in precise circuits
which provide distinct functionality, this is controlled in development. These
circuits can be a locus of dysfunction which means a dysfunction of circuits
can result in pathology. These circuits perform computations and undergo
plasticity (a high plastic region is the hippocampus). There are many types (>
100) of neurons which can be classified in many ways (for example based on
neurotransmitter synthesis).
Nervous system development - an introduction 1
, Some species, when born, can directly walk and feed themselves which is not
the case for humans. There is a difference in development of neuronal circuits.
Major events in nervous system and circuit
development
There are many important aspects that happen during development:
Embryogenesis
Patterning
Proliferation and neurogenesis
Apoptosis
Migration
Differentiation
Axon guidance
Synaptogenesis
Early neural activity
The brain develops early (the primordial hippocampus is established after the
first month) in utero and increases in size (which increases connectivity) and is
shaped post-natal.
Embryogenesis
Most of the cells that make up the body are generated here.
Nervous system development - an introduction 2
, After fertilization the egg undergoes multiple division to form a blastula
blastoceul. The cells starts moving in a stereotypical way which is called
gastrulation and the 3 primordial germ-layers are formed (ectoderm, mesoderm
and endoderm). All the cells that make up the nervous system are made from
the ectoderm (yellow) → this process is called neural induction which is the
earliest start point of neural development and it is a specialization of ectoderm
to neurectoderm/neural plate.
Spemann and mangold: they excited a small part of the neurectoderm and
inserted it in another location which still resulted in the generation of neural
tissue → subregions of the developing embryo are sufficient and necessary to
induce development of large fields of tissue, lots of information is contained in
specific tissue regions.
To push through to form a full functional brain chemicals are needed.
Nervous system development - an introduction 3
, Later in neuronal development the
neurectoderm development is guided from
factors released from the mesoderm. The
release of these factors allows the
neurectoderm to form the neural tube, the
neural plate folds up to form the neural tube →
this process is called neurulation. This tube is
a fluid filled cavity lined with cells.
The neural tube closes (zips up) in a posterior to anterior gradient until it is fully
closed.
Also at a cellular level many things have changed to form the neural tube:
They have to weaken their connection with each other
They have to change their shape
They have to make other connections
…
Closure can be impacted by genetic and environmental factors. Failure of
neural tube closure results in severe malformations (such as spina bifida or
hydrocephalus).
Nervous system development - an introduction 4
, The neural epithelium (tube) gives rise to the entire adult nervous system and
all circuits. The tube will start twisting giving rise to a complicated interior
resulting in the ventric system → the ventric system consists of remnants of the
neural tube.
The retina develops as an invagination of the diencephalic neural tube. Cells
will start moving inward and become specialized forming different structures of
the eye.
Patterning
= molecular and cellular specification of areas of developing tissue.
There are 2 different parts of patterning:
How does the neural tube know what is bottom and top.
How does the neural tube what is front and back.
How to know what is dorsal and ventral
The dorsal roots are incoming sensory information while the ventral roots is
where motor neurons are which will innervate the muscles.
1. Sonic hedgehog protein: this protein is primarily localized ventrally in the
notochord (it is labelled the strongest in the ventral side). It is synthesized
and released by the ventral notochord, where its presence induces the
expression of genes encoding this protein.
⇒ Shh is the ventralizing factor. When cells know they are ventral they
differentiate into motor neurons.
Nervous system development - an introduction 5
an introduction
Confidence Confident
Moment of
@February 12, 2024
lecture
Review @February 13, 2024
Lecture 1_NEURAL DEVELOPMENT ELLENDER
Materials
HANDOUT_240212_154818.pdf
Last Edited @March 12, 2025 9:36 AM
System neuroscience is at the intersection of neuroscience and systems
biology. You study the function of the neuronal circuit and it’s functions. We
zoom out in a way to look how cells work, how they form a neuronal network
and how these networks sustain a basis to basis to generate sensory
integration with cognition.
In the lecture series we will go from cellular to higher level cognition.
It is also important to know the different methods that are used as well as their
advantages and disadvantages. Here we want to have a combination of
research and education → therefore a lot of guest lectures are given. We need
to know the bigger picture and not specific papers.
Introduction
The aim of discussing brain development is that you look at different circuits in
the brain and how they arise (how do neurons wire in a certain way, etc).
Neurons connect with each other, in a very complex and extensive way (they
can be approximately 30 cm). Neurons wire up precisely in precise circuits
which provide distinct functionality, this is controlled in development. These
circuits can be a locus of dysfunction which means a dysfunction of circuits
can result in pathology. These circuits perform computations and undergo
plasticity (a high plastic region is the hippocampus). There are many types (>
100) of neurons which can be classified in many ways (for example based on
neurotransmitter synthesis).
Nervous system development - an introduction 1
, Some species, when born, can directly walk and feed themselves which is not
the case for humans. There is a difference in development of neuronal circuits.
Major events in nervous system and circuit
development
There are many important aspects that happen during development:
Embryogenesis
Patterning
Proliferation and neurogenesis
Apoptosis
Migration
Differentiation
Axon guidance
Synaptogenesis
Early neural activity
The brain develops early (the primordial hippocampus is established after the
first month) in utero and increases in size (which increases connectivity) and is
shaped post-natal.
Embryogenesis
Most of the cells that make up the body are generated here.
Nervous system development - an introduction 2
, After fertilization the egg undergoes multiple division to form a blastula
blastoceul. The cells starts moving in a stereotypical way which is called
gastrulation and the 3 primordial germ-layers are formed (ectoderm, mesoderm
and endoderm). All the cells that make up the nervous system are made from
the ectoderm (yellow) → this process is called neural induction which is the
earliest start point of neural development and it is a specialization of ectoderm
to neurectoderm/neural plate.
Spemann and mangold: they excited a small part of the neurectoderm and
inserted it in another location which still resulted in the generation of neural
tissue → subregions of the developing embryo are sufficient and necessary to
induce development of large fields of tissue, lots of information is contained in
specific tissue regions.
To push through to form a full functional brain chemicals are needed.
Nervous system development - an introduction 3
, Later in neuronal development the
neurectoderm development is guided from
factors released from the mesoderm. The
release of these factors allows the
neurectoderm to form the neural tube, the
neural plate folds up to form the neural tube →
this process is called neurulation. This tube is
a fluid filled cavity lined with cells.
The neural tube closes (zips up) in a posterior to anterior gradient until it is fully
closed.
Also at a cellular level many things have changed to form the neural tube:
They have to weaken their connection with each other
They have to change their shape
They have to make other connections
…
Closure can be impacted by genetic and environmental factors. Failure of
neural tube closure results in severe malformations (such as spina bifida or
hydrocephalus).
Nervous system development - an introduction 4
, The neural epithelium (tube) gives rise to the entire adult nervous system and
all circuits. The tube will start twisting giving rise to a complicated interior
resulting in the ventric system → the ventric system consists of remnants of the
neural tube.
The retina develops as an invagination of the diencephalic neural tube. Cells
will start moving inward and become specialized forming different structures of
the eye.
Patterning
= molecular and cellular specification of areas of developing tissue.
There are 2 different parts of patterning:
How does the neural tube know what is bottom and top.
How does the neural tube what is front and back.
How to know what is dorsal and ventral
The dorsal roots are incoming sensory information while the ventral roots is
where motor neurons are which will innervate the muscles.
1. Sonic hedgehog protein: this protein is primarily localized ventrally in the
notochord (it is labelled the strongest in the ventral side). It is synthesized
and released by the ventral notochord, where its presence induces the
expression of genes encoding this protein.
⇒ Shh is the ventralizing factor. When cells know they are ventral they
differentiate into motor neurons.
Nervous system development - an introduction 5
