Neurogenesis, Migration, and Post-natal Devel.

Question 1

Name some short-range (contact dependent) attractants for the growth cone.

Answer 1

• cadherins
• CAMs
• collagen
• laminin
• fibronectin
• proteoglycans

Question 2

In the hindbrain (rhombencephalon), ____ plays a role in defining the identity of each segment.

Answer 2

cell death

Question 3

What is multiple/polyneuronal innervation?

Answer 3

each muscle fiber is initially innervated by several motor neurons

Question 4

When do the caudal portions of the corticospinal tract become myelinated?

Answer 4

after birth

Question 5

Synapse formation involves _____ to a _____.

Answer 5

conversion of the growth cone to a presynaptic terminal

Question 6

What physical changes are seen in apoptosis?

Answer 6

• nuclear and cytoplasmic condensation
• DNA fragmentation

Question 7

Name 2 ways the growth cone is guided.

Answer 7

1. long range chemotaxis
2. local subtle cues (contact dependent)

Question 8

What are semaphorins?

Answer 8

long range (diffusible) repulsive molecules

Question 9

Normally, during the first postnatal year, the density of cortical dendritic spines ____ as dendritic spines ____.

Answer 9

increases; thicken

Question 10

What is the difference btw an axon and a dendrite?

Answer 10

• axons= long, send signals to target neurons
• dendrites = shorter, stubbier, receive signals from input neurons

Question 11

At birth, the density of neural connections is ____.

Answer 11

low

Question 12

_____ serve as important regulators of neuronal survival, development, and function.

Answer 12

Neurotrophins

Question 13

How does microcephaly occur?

Answer 13

not enough neurogenesis –> small brain

Question 14

What are netrins?

Answer 14

long range (diffusible) attractant OR repulsive molecules

Question 15

Growth cone guidance cues over long distances are _____.

Answer 15

diffusable

Question 16

What can disruption of axon outgrowth in development lead to?

Answer 16

mental retardation

Question 17

What is selective synapse elimination?

Answer 17

reducing the excess of contacted cells from multiple motor neurons innervating one muscle fiber to a 1:1 relationship

Question 18

The neural crest dorsal stream gives rise to the _____.

Answer 18

pigment cells

Question 19

____ and _____ are components of the ECM that are involved in neural crest cell migration.

Answer 19

Laminin and fibronectin

Question 20

What induces differentiation and formation of processes?

Answer 20

neurotrophins

Question 21

What do cadherins, CAMs, collagin, laminin, fibronectin, and proteoglycans all have in common?

Answer 21

they are short-range (contact dependent) attractants for the growth cone

Question 22

In MS, there is ______ of the CNS axons.

Answer 22

demyelination

Question 23

Neutrophins interact with membrane receptors that are members of the tropomyosin-related kinase (Trk) family, including ____, ____, and _____.

Answer 23

TrkA, TrkB, and TrkC

Question 24

Name some short-range (contact dependent) repellants for the growth cone.

Answer 24

• semaphoris
• ephrins
• tenascin

Question 25

Name 7 neurotrophic factors.

Answer 25

1. NGF
2. BDNF
3. NT-3
4. NT–4/5
5. CNTF
6. LIF
7. cardiotropin

Question 26

How are GABA receptors different en utero?

Answer 26

• receptors have many different subuints and isoforms
• eq potential for Cl- is lower
• Cl- levels are higher
• activation of GABA receptors is excitatory

Question 27

What do neurotrophic factors do?

Answer 27

promote cell survival

Question 28

What is the neurotrophic hypothesis?

Answer 28

there is a limited amount of nutrients and trophic factors provided by the synapse targets to establish proper neuronal connections

Question 29

What do semaphoris, ephrins, and tenascin all have in common?

Answer 29

they are short-range (contact dependent) repellants for the growth cone

Question 30

CNS neurons appear to need _____ for survival.

Answer 30

multiple neurotrophic factors

Question 31

Even if axons can be induced to grow across a lesion, what will probably go wrong?

Answer 31

it’s unlikely that they will make the same connections as before the injury

Question 32

What is the growing tip of the axon called?

Answer 32

the growth cone

Question 33

The neural crest ventral stream gives rise to the _____.

Answer 33

sensory, autonomic, and enteric ganglia

Question 34

Synapse elimination is due to _____.

Answer 34

competition for the target (NOT death)

Question 35

_____ are involved in outgrowth, adhesion, and fasciculation.

Answer 35

CAMs

Question 36

When does myelination begin?

Answer 36

during embryonic development in the periphery

Question 37

These are long range (diffusible) attractant molecules.

Answer 37

netrins

Question 38

Local growth cone guidance cues are ______ and require _____.

Answer 38

bound to cell membranes or ECM and require direct cell contact

Question 39

______ are examples of short-range contact dependent signals.

Answer 39

CAMs

Question 40

_____ abnormalities are associated with Down’s Syndrome.

Answer 40

Dendritic

Question 41

Where is the first CNS location that is myelinated? When?

Answer 41

the spinal cord @ the end of the 1st trimester

Question 42

____ is associated with abnormal social/emotional behaviors.

Answer 42

ASD

Question 43

During the first prenatal year, the brains of ASD show ______, especially in white matter areas, and _____.

Answer 43

abnormally high increases in size; neuronal cell bodies are smaller and dendrites branch less

Question 44

_____ inhibit apoptotic cell death programs.

Answer 44

Neurotrophic factors

Question 45

These are long range (diffusible) repulsive molecules.

Answer 45

semaphorins, netrins