Neuron Development

Question 1

What do radial glial cells do for the genesis of neurons?

Answer 1

Give rise to neurons and astrocytes and create “highways” for early neurons to follow

Question 2

What are the 5 steps of the genesis of neurons?

Answer 2

1. A cell extends upward from the ventricular zone
2. The nucleus of the cell migrated upward toward the pia & cell’s DNA is copied
3. The nucleus (2 complete sets of genes) returns to the ventricular zone
4. Cell retracts its process
5. Cell divides into a symmetrical or asymmetrical cell

Question 3

What is the difference between symmetrical cell division and asymmetrical cell division?

Answer 3

Symmetrical cell division: keeps dividing

Asymmetrical cell division: matures- never divides again

Question 4

How does cell proliferation work?

Answer 4

Cleavage plane during cell division determines fate of daughter cells. Higher concentration of Notch-1 induces neuron/glia maturation

Question 5

What is the difference between Notch-1 and Numb?

Answer 5

Notch-1 induces neuron/glial maturation, Numb allows for continued division

Question 6

What is the idea of “inside out” development? What is the first layer that cells migrate to?

Answer 6

The first layer becomes VI, then V, then IV (goes from bottom to top); First cells to migrate take up residence in “subplate” layer

Question 7

What are the 3 phases of pathway formation?

Answer 7

1. pathway 2. target 3. address

Question 8

What is the growth cone?

Answer 8

Growing tip of a neurite

Question 9

What do netrin receptors do? Where are they found?

Answer 9

Netrin receptors on growth cones attract growing axon to midline ventral spinal cord

Question 10

What does the expression of Robo do? Where is it found?

Answer 10

Once passed midline, growing axons begin expressing Robo (responds to “slit” receptor), it is repulsive to keep growing axons away

Question 11

What is apoptosis?

Answer 11

Programmed cell death

Question 12

What happens to neurons and synapses in early age? Old age?

Answer 12

In early development, neurons and synapses are overproduced. In older age we see “pruning”

Question 13

What is synaptic rearrangement? When does it take place?

Answer 13

Change from one pattern of connection to another; happens during the critical period

Question 14

What is synaptic segregation?

Answer 14

Refinement of synaptic connections by spontaneous activity

Question 15

What is the idea of “winner-takes-all”?

Answer 15

Synaptic strengthening & elimination

Question 16

What are the ocular dominance columns?

Answer 16

Segregated input from each eye

Question 17

What layer do neurons project to in order to get binocularity?

Answer 17

From Layer IV to Layer III

Question 18

What does the phrase “neurons that fire together wire together” mean?

Answer 18

Co-occuring pre- and post- synaptic activity often leads to strengthening of synapses between these 2 neurons

Question 19

What does the phrase “neurons that fire out of sync lose their link” mean?

Answer 19

Relatively strong pre-synaptic activity, together with relatively weak post-synaptic activity often leads to synaptic weakening

Question 20

What are the 2 unique properties of NMDA receptors?

Answer 20

1. Voltage-gated Ca2+ conductor

2. Co-activation detector: magnitude of Ca2+ influx signals level of pre- and postsynaptic activation

Question 21

What is a mechanism of synaptic plasticity?

Answer 21

Long-term synaptic potentiation

Question 22

What triggers the loss of AMPA receptors?

Answer 22

Weak NMDA receptor activation by poorly correlated activity

Question 23

What maintains AMPA receptors?

Answer 23

Strong NMDA receptor activation by well-correlated activity