Neuronal Development

Question 1

What percentage of synapses are eliminated after development?

Answer 1

~50%

Question 2

If the human brain were a computer, what would its storage capacity be?

Answer 2

1000TB

Question 3

What is neurogenesis?

Answer 3

Neurones are born

Question 4

What is migration?

Answer 4

Neurones find their place and build

Question 5

What is differentiation?

Answer 5

Determination of cell fate

Question 6

What is target innervation?

Answer 6

Address selection

Question 7

What is synapse formation?

Answer 7

Creation of connections

Question 8

What occurs first in neuronal development?

Answer 8

Gastrulation

Question 9

What is gastrulation?

Answer 9

Embryo transforms into a single layer of epithelial cells

Question 10

Where and when do the primitive streak and notochord form?

Answer 10

At the midline during gastrulation

Question 11

What are the three primitive cell layers that develop during gastrulation?

Answer 11

Endoderm, mesoderm, ectoderm

Question 12

How does the neural plate come about?

Answer 12

Ectoderm thickens after gastrulation

Question 13

Which epithelium gives rise to the entire nervous system?

Answer 13

Neural plate

Question 14

How is the neural groove invagination formed?

Answer 14

Uneven rates of cell division at the neural plate

Question 15

How is the neural tube formed?

Answer 15

Neural groove joins together

Question 16

hen do neural crest cells develop?

Answer 16

As the neural tube is formed

Question 17

What does the neural tube eventually become?

Answer 17

Fluid-filled cerebral ventricles of the brain and spinal cord

Question 18

Where does the roofplate form?

Answer 18

Where the neural tube closes

Question 19

Where does the floorplate form?

Answer 19

Above the notochord

Question 20

Which are the three transient structures during neural development?

Answer 20

Roofplate, floorplate, notochord

Question 21

When do the brain subdivisions become discernible?

Answer 21

After the neural tube and crest have developed

Question 22

What are the three brain subdivisions?

Answer 22

Prosencephalon, mesencephalon, rhombencephalon

Question 23

What is the proencephalon?

Answer 23

Forebrain

Question 24

What is the mesencephalon?

Answer 24

Midbrain

Question 25

What is the rhombencephalon?

Answer 25

Hindbrain

Question 26

What do neural stem cells in the neural tube replicate into by mitosis?

Answer 26

More stem cells or neuroblasts

Question 27

What are neuroblasts the precursor of?

Answer 27

Neurones

Question 27

What are neuroblasts the precursor of?

Answer 27

Neurones

Question 28

What are neuroblasts the precursor of?

Answer 28

Neurones

Question 29

When do the ventricular and marginal zones form?

Answer 29

During neurogenesis

Question 30

How do neurones find their destination during migration?

Answer 30

Move along surface of radial glia acting as guidelines

Question 31

What occurs once neurones have migrated?

Answer 31

Differentiation to form different cell populations

Question 32

Which end is the brain formed at?

Answer 32

Anterior

Question 33

What forms the spinal cord?

Answer 33

Neural tube near somites

Question 34

What forms the major components of the PNS?

Answer 34

Neural crest separating from the neural tube

Question 35

What becomes CSF ventricles?

Answer 35

Lumen of neural tube

Question 36

What in the brain distinguishes humans from other animals?

Answer 36

Size of cortex / frontal lobe

Question 37

What do morphogens do?

Answer 37

Instruct a high degree of patterning in the neural tube

Question 38

What patterning occurs along the length of the neural tube?

Answer 38

Anterior/posterior (rostral/caudal)

Question 39

What patterning occurs in the cross-section of the neural tube?

Answer 39

Dorsal/ventral

Question 40

What determines the ultimate fate of a neurone?

Answer 40

Where and when it was produced

Question 41

What is an example of morphogen gradients driving differentiation?

Answer 41

FGF/BMPs influencing transcription factors for anterior/posterior differentiation

Question 42

What are Hox genes?

Answer 42

Family of TFs that establish segmentation along the anterior/posterior axis

Question 43

What is synophthalmia?

Answer 43

Cyclopia - Development of one large eye

Question 44

How do cyclops cows come about?

Answer 44

Mother eats a certain plant, Sonic hedgehog inhibition leads to loss of ventral identity

Question 45

What are the neural precursor cells in the neural tube?

Answer 45

Neuroepithelium / neuroepithelial progenitor cells

Question 46

What do radial glia connect in the developing cortex?

Answer 46

Ventricular and pial surfaces

Question 47

What is the innermost layer of the neural tube?

Answer 47

Ventricular zone

Question 48

How are transit amplifying cells generated?

Answer 48

Asymmetrical division of cells in the ventricular zone

Question 49

What is the outermost layer of the neural tube?

Answer 49

Pial surface

Question 50

What forms the marginal zone of the cortex?

Answer 50

Neuroblasts migrating to the pial surface

Question 51

In which direction is the cortex built?

Answer 51

Inside out, with newer neuroblasts migrating past their older cousins

Question 52

How can the columnar organisation of the cortex be used to reveal the birthdate of a neurone?

Answer 52

Correlates to location like a tree ring

Question 53

Which type of cortical neural cell has a different origin to others?

Answer 53

Interneurones

Question 54

Where are cortical interneurones born?

Answer 54

Ganglionic eminences

Question 55

Where do glial cells originate?

Answer 55

Neuroepithelium

Question 56

What can glioblasts become?

Answer 56

Ependymal cells, astrocytes or oligodendrocytes

Question 57

How does a glioblast differentiate into an ependymal cell?

Answer 57

Remains attached to the lumen

Question 58

What is the function of ependymal cells?

Answer 58

Production of CSF

Question 59

How does a glioblast differentiate into an astrocyte or oligodendrocyte?

Answer 59

Moves to marginal layer

Question 60

What is the function of astrocytes?

Answer 60

Maintenance and repair

Question 61

What is the function of oligodendrocytes?

Answer 61

Myelination

Question 62

What are the two steps of target innervation?

Answer 62

Polarisation and fasciculation

Question 63

What occurs in the polarisation stage of target innervation?

Answer 63

Cell body establishes axons and dendrites

Question 64

Which part of the neurone moves during polarisation (target innervation)?

Answer 64

The growing axon - Cell body stays put

Question 65

How do growing processes navigate between stepping stones during polarisation (target innervation)?

Answer 65

Using cues and signals

Question 66

What occurs in the fasciculation stage of target innervation?

Answer 66

Axons piggy-back along existing neurones

Question 67

How do pioneering axons navigate during fasciculation (target innervation)?

Answer 67

Piggy-back along other tissue types

Question 68

What is the growth cone?

Answer 68

Tip of axon that recognises guidance signals and cues in target innervation

Question 69

What are the properties of non-diffusible guidance signals?

Answer 69

Short-range, substrate-derived, present in ECM or target cells

Question 70

What are the properties of diffusible guidance signals?

Answer 70

Long-range, act as gradients

Question 71

What are cadherins and ephrins examples of?

Answer 71

Non-diffusible guidance signals for target innervation

Question 72

What are netrin and semaphorins examples of?

Answer 72

Diffusible guidance signals for target innervation

Question 73

What is the structure of a growth cone?

Answer 73

Hand-like with surface receptors

Question 74

What are the types of growth cone?

Answer 74

Filopodia and lamellipodia

Question 75

What does the commissural interneurone determine?

Answer 75

Left-right coordination

Question 76

What is the first attraction experienced by the commissural interneurone during development?

Answer 76

Long-range attraction to the floorplate

Question 77

What happens after the commissural interneurone reaches the floorplate?

Answer 77

Growth cone switches sensitivity from attractive to repulsive to leave the area so it crosses the midline once

Question 78

Why don't motor neurones cross the midline?

Answer 78

Midline always repulsive, they don't need to cross

Question 79

How does the growth cone move towards or away from guidance cues?

Answer 79

Actin cytoskeletal changes

Question 80

Once the direction of an axon is determined, how is it laid down in the desired location?

Answer 80

Microtubular cytoskeletal changes

Question 81

What do adhesion molecules do?

Answer 81

Stabilise formed connections between neurones

Question 82

What do presynaptic neurexins do?

Answer 82

Organise the synaptic vesicle docking zone

Question 83

What do postsynaptic neuroligins do?

Answer 83

Recruit postsynaptic receptors

Question 84

How is the final pattern of neural contacts determined?

Answer 84

Neurotrophins and electrical activity

Question 85

Why are synapses and cells made in excess and then abandoned as needed?

Answer 85

To ensure robust, functionally required circuits

Question 86

What happens when a limb is removed from a foetus?

Answer 86

Reduced motor and sensory neurones in the spinal cord

Question 87

What happens when a limb is grafted onto a foetus?

Answer 87

Increased motor pool where the extra limb is grafted

Question 88

How does the target regulate neurone circuits?

Answer 88

Continued release of trophic factors, and activity