CNS Development Flashcards
Name the scientific name for the main brain regions, Forebrain, Midbrain and Hindbrain.
Prosencephalon, Mesencephalon, Rhombencephalon.
Name the sub-groups of the three main brain regions; Prosencephalon, Mesencephalon and Rhombencephalon, and what they contain.
(1) Prosencephalon:
- Telencephalon: Isocortex, basal ganglia and limbic system
- Diencephalon: Thalamus and Hypothalamus
(2) Mesencephalon:
- Tectum and Tegmentum
(3) Rhombencephalon:
- Metencephalon: Cerebellum and Pons
- Myelencephalon: Medulla
When does the CNS begin to form?
3 Weeks.
What do the front part and rest of the neural tube differentiate into?
Front part: Forebrain, Midbrain, Hind brain
Rest: Spinal cord
What is “Neurolation” and name the four stages of it.
Formation, bending, shaping and closure.
Neurolation refers to the folding and transformation process of the neural plate into the neural tube.
What is understood by “cell migration” in the Neural tube?
Cells migrate from the inner part to the outside of the neural tube to form main brain regions.
What are “Neuromeres” (A.) and when do they appear (B.)?
A. Series of swellings, segments of the neural tube that establish the embryonic brain during development: Prosomeres, Mesomeres, Rhombomeres.
B. Week 4/ Day 28
During early development the brain folds at three locations. Where and when?
- Mesencephalic flexure; pontine flexure; cervical flexure.
- Week 4-8
When does the brain develop from 3- to 5 vesicle stage?
Week 5
Explain, what is understood by structural and functional brain components?
- Structural: Nuclei/ grey matter are clusters of neural cell matter and Tracts/ white matter are connecting pathways of different parts of the brain.
- Functional: Neuronal system are a collection of nuclei system that serve a common function.
What do we understand by Sulci, Gyri and Fissures?
Sulci are minor furrows, Gyri are rims and Fissures are deep furrows.
What is “Cephalization” and when is it completed?
- Gradual appearance of Gyri and Sulci.
- After 9 months.
When does the division of the two brain halves first appear?
Week 14.
When is the nerve cell generation completed?
After 5 months.
How are telencephalon and diencephalon positioned to each other?
Telencephalon is folded on top of diencephalon.
What does white matter contain of?
Myelin & internal capsule, so it is highway for communication.
What are the four subregions of the neocortex and what are their main functions?
- Frontal cortex
- High-level cognition
- Vizual-motor planing - Parietal cortex
- Sensory integration
- Motor control
- Expressive language - Temporal cortex
- Auditory and visual processing
- Receptive language - Visual cortex
- High-level visual processing
In what sense are neurons post-mitotic?
They are unable to divide once established.
What does the message from a neutron depend on?
The type of message depends on the type of receptor.
What are the major building blocks of a neuron?
Dendrites, soma (cell body), axon and synapse.
How do we express the diversity of neurons (classification)?
- Structural:
- Anaxonic neuron
- Bipolar neuron
- Unipolar neuron
- Multipolar neuron - Funcitonal:
- Motor neuron
- Interneuron
- Sensory neuron
What are the main functions of glia cells?
- Provide physical and chemical support to neurons
- Maintain neural environment
- Help in neural communication
Name Glia cells of the CNS and PNS and their main functions.
CNS
1. Astrocytes
2. Oligodendrocytes
3. Ependymal cells
4. Microglia
PNS
1. Schwann cells
2. Satellite cells
Explain the relationship between Myelination and Multiple Sclerosis.
Inflammation of the myelin sheet causes impairment of the cell communication.
Name the eight phases of Fetal- and Embryonic brain development. Mind, that they can occur simultaneously in different brain parts.
- Mitosis/ Proliferation
- Migration
- Differentiation
- Aggregation
- Synaptogenesis
- Neuron death
- Synapse rearrangement
- Myelination
What are the two types of division of neural tube epithelia?
- Symmetric division:
- 2 Stemm cells or 2 committed cells - Asymmetric division:
- 1 Stemm cell and 1 committed cell
What cell types arise from asymmetric division of neural tube epithelia?
- Radial glia
- Glioblasts
- Neuroblasts
- Ependymal cells
Which factors are needed to turn Ectoderm into Epidimes?
High BMP4
Low Chordin and Noggin
Which factors are needed for “Neural induction”, from Neural tube ectoderm into Neuroectoderm?
High Chordin and Noggin
Low BMP4
Which factors are needed to specify Neural tube Organization Centers?
Roofplate: TGF-betaS
Floorplate: SHH
Which factors are needed for “Neurogenesis”, to form neural progenitors which eventually give rise to neurons?
High bHLH gene products
Low Notch
Which factors are needed for “Oligodendrogenesis” to form Olygodendrocytes?
High Olig1/2 and Nkx2.1
Low bHLH gene products
Which factors are needed for “Astrogliogenensis” to form astrocytes?
High Notch/ Nrg
Low bHLH gene products
Where does Mitosis (1.) occur and what happens to the cells afterwards?
- Mitosis occurs in the ventricular zone (/layer)
- Cells enter post-mitotic state
Explain the role of Radial glia cells in migration (2.).
Migrating neurons follow radial glia cells from the inside to the outside.
How does the movement during migration (2.) occur?
Actin bundles called “Growth cones” crawl forward and drag the attached axon behind them.
How do neurons during migration (2.) know where to go?
- Extrinsic signals
- Chemoattraction (e.g. Netrins)
- Chemorepulsion (e.g. Semaphorins) - Intrinsic Receptors
- Protein receptors detect signals made by cells
Describe the cause and symptomology of Microcephaly, Lissencephaly, Inverted cortical layering and Double cortex.
- Microcephaly
- Initiation defect caused by mutation in Filamin and Argef2 - Lissencephaly
- Ongoing migration defect caused by mutation in Lis1 and Dcx
- Leading to a loss of cortical layering
Or
- Leading to double cortex - Inverted cortical layering
- Lamination defect caused by mutation in Reelin and Apoer2 - Double cortex
- Stop signal defect caused by mutation in DCX
Synaptogenesis (5.) gives rise to different types of synapses, which are they?
- Axo-dendric
- Axo-somatic
- Axo-axotic
- Dendro-dendritic
Who guides neurons during Synaptogenesis (5.)
- Little extrusions called “spines” along axons and dendrites
- Guidance molecules; such as adhesion molecules, neurotrophins and ligand-receptor pairs.
What are the three steps of Synaptogenesis (5.)?
- Localised cellular interactions or adhesions
- Pre-synaptic differentiation to build synapse
- Post-synaptic differentiation to receive neurotransmitter signals
In what sense are proto- cadherins combinatorial molecular codes for synapse specificity?
Alternative Splicing forms specific pre- and postsynaptic combination of juxtacrine signaling molecules.
In what way are cell death (6.) and rearrangement (7.) related?
Neurons receiving insufficient neutropic factors die.
So that axonal process compete for neutropic factor and rearrange accordingly.
When does myelination (8.) begin?
At 5 months. Done by oligodendrocytes to increase conduction speed. “Saltatory conduction”
Where do we find the “red nucleus” and the “substantia nigra”.
In the mesencephalon/ midbrain.
What gives the red nucleus its “colour”?
Haemoglobin and ferritin
What gives the substantia nigra its “colour”?
Neuromelanin
What is the function of the red nucleus?
It is an additional motor pathway for the coordination of sensorimotor information.
What is the function of the substantia nigra?
Involved in Dopamine production for movement control, cognitive executive functions and limbic activity
Which neural tissues does the diencephalon give rise to?
- Thalamus
- Subthalamus
- Hypothalamus
- Neuropituitary
How are the eyes, optic tract and chasm connected?
Via the floor plate.
The “infundibulum” differentiates to form which structure?
Posterior pituitary lobe.
What is the function of the “pineal gland”?
Melatonine Production
Light sensing
What is the function of the “thalamus”?
Information relay for sleep, wakefulness, consciousness, learning and memory.
What is the function of the “pituitary gland”?
Hormone production
Regulation of growth, metabolism and reproduction
What are the functions of the “hypothalamus”?
Hormone Production
Regulates hormone secretion of pituitary gland
Regulates autonomic nervous system
Regulates endocrine systems
Regulates goal-directed behaviours
What are the four sup compartments of the “telencephalon”/ hemispheric wall?
- Olfactory bulb
- Striatum
- Neocortex (90% of cerebral cortex)
- Hippocampus
Where is the cause for Huntington’s disease, Hemibalism and Parkinsons located?
Basal ganglia.
How do we call the spatial representation of body parts in the primary motor and sensory cortex?
Cortical Homunculus.
What are the four integrative centres of the the brain?
- General interpretive center (Wernicke’s area)
- Speech center (Broca’s area)
- Hemispheric lateralisation
- Prefrontal cortex
Which system do amygdala and hippocampus belong to?
Limbic system
What are the main functions of amygdala and hippocampus?
Amygdala: Emotion, Emotional memory
Hippocampus: Navigation, memory
