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SG Molecular > Lecture 31: Neural Development > Flashcards

Lecture 31: Neural Development Flashcards

1
Q

There are 3 phases of neural development. What is characteristic of phase 1?

A

Different cell types develop independently at widely separate locations in the embryo and are unconnected

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2
Q

There are 3 phases of neural development. What is characteristic of phase 2?

A

Axons and dendrites grow out along specific routes, setting up provisional orderly network of connections between various parts of the system

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3
Q

There are 3 phases of neural development. What is characteristic of phase 3?

A

Connections are adjusted and refined through interactions with distant regions via electric signals

This phase continues throughout adult life

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4
Q

Neurons are produced in association with what other cell type?

A

Glial cells

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5
Q

What is the function of glial cells in relation to neurons?

A

Glial cell provide supporting framework and nutrition to neurons

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6
Q

Both neurons and glial cells develop from __________ from a common precursor

A

Ectoderm

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7
Q

What are the 3 components of the CNS?

What is the CNS derived from?

A

Brain, spinal cord, retina

Derived from neural tube

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8
Q

What are the 2 components to the PNS?

What is the PNS derived from?

A

Nerves, sensory neurons

Derived from neural crest

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9
Q

The neural tube is derived from a single layered epithelium. It starts with a _______________ on the dorsal side of the embryo, and gradually deepens as _____________ become elevated, ultimately closing as a neural tube

A

Neural groove

Neural folds

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10
Q

What is the center of the neural tube called?

A

Neural canal

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11
Q

What type of signaling pathway controls differentiation into neurons? How does it do this?

A

Delta Notch

Lateral inhibition and positive feedback

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12
Q

Signal proteins secreted from ventral and dorsal sides of neural tube act as opposing ___________, causing neurons at different dorsoventral positions to express different gene regulatory proteins

A

Morphogens

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13
Q

What morphogen is secreted by the roof plate of the neural tube?

A

BMP (TGF-beta family)

These have to do with pattern formation and secretion of extracellular matrix

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14
Q

What morphogen is secreted from the floor plate of the neural tube?

A

Shh

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15
Q

Neural crest cells originate from which end of the neural tube?

A

Dorsal end

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16
Q

___________ is the process by which the neural tube actually closes

A

Neurulation

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17
Q

Neurulation results in what 3 cell types?

A

Neurons and glial cells of the PNS

Epinephrine producing cells of the adrenal gland

Many of the skeletal and connective tissue components of the head

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18
Q

What does the fate of neural crest cells depend on?

A

Depends on where they migrate to and settle

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19
Q

The migration of neurons in the neural tube is facilitated by the ability to crawl along the length of the neural tube on what type of cell process?

A

Radial glial cell processes

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20
Q

T/F: The first round of cortical neurons to divide tend to migrate the furthest distance

A

False - cells that divide first travel the least distance, cells that divide later must travel beyond each layer of cortical neurons that has already formed

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21
Q

The tip of an axon or dendrite has an irregular, spiky enlargement called a _____________

A

Growth cone

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22
Q

How do growth cones work?

A

They crawl through surrounding tissue, trailing the axon or dendrite behind

They have an “engine” and “steering apparatus” that direct the process

23
Q

What dictates growth cone behavior?

A

Cytoskeletal machinery

24
Q

What two things are “thrown out” by growth cones?

A

Filopodia

Lamelopodia

25
Q

What 2 monomeric GTPases control assembly/disassembly of actin filaments, thus controlling the movement of the growth cone?

A

Rho and Rac

26
Q

Growth cones travel towards target cells along predictable routes. What two major cues do growth cones exploit to find their way?

A

Extracellular matrix environment (sensed by receptors present on the membrane)

Chemotactic factors released by neighboring cells (may be attractive or repulsive)

27
Q

_____________ ___________ is the process by which growth cones follow a path taken by other cells

A

Contact guidance

28
Q

Contact guidance is mediated by what type of molecules?

A

Homophobic cell adhesion molecules

29
Q

What are the 2 important classes of homophilic cell adhesion molecules?

A

Immunoglobulin superfamily

Cadherin family

30
Q

What type of matrix molecules favor axonal outgrowth?

A

Laminin

31
Q

What type of matrix molecules inhibit axonal outgrowth?

A

Chondroitin sulfate proteoglycans

32
Q

What are the 6 mechanisms of growth cone guidance?

A 
ECM adhesion
Guidance by pioneer neuron
Contact inhibition
Cell surface adhesion
Chemoattraction
Chemorepulsion
33
Q

__________ neurons of the spinal cord receive and relay sensory info from sensory neurons located in the periphery of the body

A

Dorsal

34
Q

___________ clusters of spinal cord neurons develop as motor neurons and send out long axons to connect with specific subsets of muscles

A

Ventral

35
Q

Intermediate locations have _____________ that connect specific sets of nerve cells to each other

A

Interneurons

36
Q

Where are growth cones located during spinal cord development in terms of sensory, motor, and interneurons?

A

Growth cone of sensory neuron is ENTERING spinal cord

Growth cone of motor neuron is LEAVING spinal cord

Growth cones of interneurons remain inside spinal cord

37
Q

What path do commissural neurons take?

A

They come from roof plate, grow vertically downward then take sudden 90 degree turn, abruptly leaving

38
Q

The path of commissural neurons is due to the force of chemotactic factors. Name the chemoattractant discussed in class

A

Netrin

39
Q

The path of commissural neurons is due to the force of chemotactic factors. Name the repulsive chemotactic factors discussed in class.

A

Slit and Semaphorin

40
Q

The binding of the chemoattractant Netrin by cells of the floor plate leads to what?

A

Netrin binds to its receptor, causes opening of TRPC channels and allows entry of extracellular calcium

This leads to activation of machinery for extension of filopodia and movement of the growth cone

41
Q

T/F: Non-commisural neurons in the neural tube do not have netrin receptors, so they do not migrate toward the floor plate

A

True

42
Q

During commissural neuron guidance, midline cells secrete ________

A

Slit

43
Q

What is the receptor for Slit?

A

Roundabout

44
Q

What is the action of slit?

A

Repels growth cones and blocks entry to the midline

45
Q

What do target cells secrete to signal the axonal growth to stop and synapse?

A

Growth factor (neurotropic factors)

46
Q

What happens to cells that receive adequate growth factor? What about the ones that don’t?

A

Cells that receive adequate growth factor will form synapses

Cells that do not get adequate growth factor will die off

47
Q

What was the first prototypical neurotrophic factor to be identified?

A

Nerve growth factor (NGF)

48
Q

What family does nerve growth factor (NGF) belong to?

What type of receptor does it bind?

A

Belongs to family of neurotrophins

NGF receptor is a tyrosine kinase (TrkA)

49
Q

What is the action of nerve growth factor (NGF)

A

Promotes survival of specific sensory neurons and sympathetic neurons

50
Q

What are the short term effects of nerve growth factor (NGF)?

A

Local, direct, and rapid effect on growth cone and neurite extension independent of communication with cell body

51
Q

What are the long term effects of nerve growth factor (NGF)?

A

Effect on cell survival

Mediated by its receptor (TrkA), uptake into cells via endocytosis and stimulation of downstream signaling pathways

52
Q

Retinal neurons show selectivity for tectal position.

The posterior retina moves favorably along which part of the tectum?

A

Anterior

53
Q

What chemotactic factor is responsible for the selectivity of retinal neurons for tectal position? Is it stimulatory or inhibitory?

A

Ephrin; inhibitory

54
Q

Neurons that fire together wire together - meaning that synapses are strengthened by external events that cause 2 or more neurons to be activated at the same time. How does this apply to memory?

A

The more you stimulate a certain nerve pathway (like studying), the increasing strength of that synapse via calcium entry through NMDA receptor. This eventually leads to individual dendritic spine remodeling, and new ones forming

SG Molecular (7 decks)

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