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Questions and Answers
What is the primary role of morphogens in the neural tube during development?
What is the primary role of morphogens in the neural tube during development?
During peak times of neurogenesis, how many nerve cells are added per minute?
During peak times of neurogenesis, how many nerve cells are added per minute?
Which structure is NOT considered a transient structure essential for nervous system formation?
Which structure is NOT considered a transient structure essential for nervous system formation?
What process occurs after the neural plate folds inwards during neurogenesis?
What process occurs after the neural plate folds inwards during neurogenesis?
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What is the significance of the anterior end of the neural tube in development?
What is the significance of the anterior end of the neural tube in development?
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What role do morphogen gradients play in neurogenesis and differentiation?
What role do morphogen gradients play in neurogenesis and differentiation?
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Which statement accurately describes the influence of transcription factors during neuron development?
Which statement accurately describes the influence of transcription factors during neuron development?
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What does the presence of Hox genes indicate in embryonic development?
What does the presence of Hox genes indicate in embryonic development?
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Which of the following correctly describes the significance of the cortex in human brains compared to other animals?
Which of the following correctly describes the significance of the cortex in human brains compared to other animals?
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What is demonstrated by the experiment involving the grafting of tissue from a pigmented to a non-pigmented amphibian embryo?
What is demonstrated by the experiment involving the grafting of tissue from a pigmented to a non-pigmented amphibian embryo?
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What is the approximate number of neurons in the human brain?
What is the approximate number of neurons in the human brain?
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During brain development, what percentage of synapses are typically eliminated?
During brain development, what percentage of synapses are typically eliminated?
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Which process describes the birth of neurons?
Which process describes the birth of neurons?
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What is required for neurons to find their proper location in the brain?
What is required for neurons to find their proper location in the brain?
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Which key concept underlies every function of the nervous system?
Which key concept underlies every function of the nervous system?
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What storage capacity is estimated for the human brain?
What storage capacity is estimated for the human brain?
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Which process involves the formation and selective elimination of synapses?
Which process involves the formation and selective elimination of synapses?
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Study Notes
Brain Development and Construction of Neural Circuits - I
- The human brain contains ~100 billion neurons, each forming thousands of connections.
- Approximately 1 quadrillion synapses are formed during development, with over 50% eliminated.
- Estimate of the brain's storage capacity is ≥1 petabyte (~1000 terabytes).
- The challenge is how the brain creates the correct number and type of cells in the right place, at the right time, and assembles them into functional neural circuits.
The Challenge
- Key questions include:
- How does the brain generate the correct number of cells?
- How does the brain generate the right type of cells?
- How are cells positioned correctly?
- How are cells assembled into functional neural circuits within the appropriate timeframes?
Development of the Brain
- A one-month-old embryo is shown as an example of early development.
Different Neuron Types
- Diagrams of unipolar, pyramidal, multipolar, bipolar, and Purkinje neurons are provided. These illustrate various neuron shapes and are important because neurons come in many shapes and forms.
Glial Cells
- Images depicting fibrous astrocytes, oligodendrocytes, protoplasmic astrocytes and microglial cells are shown.
- Glial cells greatly aid in supporting neurons.
Nervous System Functions
- Sensing changes in the external environment.
- Responding based on instinct and experience.
- Deciding what action to take, considering factors like instinct and prior experiences.
One Cell Giving Rise to the Nervous System
- The aim is to explore the key stages in the development of the nervous system.
- Learning outcomes include describing the processes of neurogenesis, differentiation, and migration, as well as target innervation and synapse formation and elimination.
Neurogenesis
- Formation of the notochord at the midline of the embryo.
- Ectoderm develops into neuroectoderm.
- Precursor cells of neuroectoderm carry out neurulation.
- Neurulation will lead to the generation of the nervous system
Neurogenesis - Continued
- The neural plate folds inward to form the neural tube.
- The floorplate sits above the notochord.
- The neural tube closes to form the neural tube.
- Neural crest cells develop.
- Transient structures like the notochord, floorplate, and roofplate are essential in instructing the formation of the nervous system.
- The anterior end of the neural tube (forebrain) forms the brain.
- Neural tube near somites forms the spinal cord.
- Neural crest separates from the neural tube to form the PNS.
- The lumen of the tube becomes the ventricles, filled with CSF.
- Stages of development are shown in diagrams.
Neurogenesis and Differentiation: How Do Neurons Become Different?
- High degree of patterning exists in the neural tube.
- Patterning is dependent on anterior/posterior (rostral/caudal) along the neural tube, as well as dorsal-ventral sections.
- Morphogens instruct patterning.
How does This Develop into a Brain?
- Diagrams show the progression of the neural tube into regions including the midbrain, hindbrain and forebrain, culminating in a 9-month-old brain.
How does This Develop into a Brain? (cont.)
- The size of the cortex, particularly the frontal lobe, distinguishes humans from animals.
- The brain distinguishes the individual.
Neurogenesis and Differentiation
- The stage and location of a neuron's birth affect its ultimate fate.
- Morphogen gradients drive differentiation.
- Example morphogens, such as FGF, Wnt, and BMPs, are identified.
How Morphogens Act
- Morphogens bind to receptors, activating or repressing sets of transcription factors.
- Transcription factors control gene expression programs.
- Gene expression profiles determine cell identity.
- Distance from morphogen source, plus availability of ligand and receptors, influence responses in cells.
Hox Genes
- Hox genes are a family of transcription factors that help to pattern the anterior-posterior body axis.
- They determine segmentation in the body.
How Do We Know Cell Fate Can Be Induced?
- Grafting experiments of tissue from a pigmented area to one that is not pigmented in an amphibian embryo demonstrates cell fate induction.
- The transplantation of cells can induce a secondary axis in their host cells.
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Description
Test your knowledge on the crucial role of morphogens and the development of the neural tube in embryology. This quiz covers essential aspects of neurogenesis, including the influence of transcription factors and the significance of Hox genes. Challenge yourself to answer questions related to neural differentiation, structure significance, and neuron statistics.
