Chapter 23: Wiring the Brain

Question 1

In which three stages do neuronal structures develope?

Answer 1

Cell proliferation
Cell migration
Cell differntiation

Question 2

What is meant by cell differentiation?

Answer 2

The process in which a cell takes on the appearance and characteristics of a neuron.

Question 3

What are neuroblasts?

Answer 3

Immature Neurons

Question 4

What is the extracellular matrix?

Answer 4

Space between cells (can contain proteins, if appropiate cell growth occurs)

Question 5

To which kind of molecules is fasciculation due?

Answer 5

Cell-adhesion molecules.

Question 6

Name an example for a chemoattractant.

Answer 6

Netrin.

Question 7

What is a chemorepellent? Name an example.

Answer 7

A diffusable molecule that chases axons away.

Slit.

Question 8

What does the chemoaffinity hypothesis say?

Answer 8

Chemical Markers on growing axons are matched with compelmentary chemical markers on their targets to establish precise connections.

Question 9

Cell death reflects competition for what?

Answer 9

Trophic factors

Question 10

What was the first trophic factor to be identified?

Answer 10

Nerve Growth Factor.

Question 11

What is apoptpsis?

Answer 11

The systematic disassembly of the neuron.

Question 12

What is the synaptic capacity of a neuron?

Answer 12

The finite number of synapses a neuron can recieve on its dendrites and soma.

Question 13

Synaptic rearrangement is the final step of address selection. It occurs as a consequence of…..

Answer 13

neural acitivity and synaptic transmission

Question 14

What are the two simple rules for synaptic modification?

Answer 14

1. neurons that fire together wire together

2. neurons that fire out of sync lose their link

Question 15

Explain the 5 Positions in cell proliferation

Answer 15

1. A cell in the ventricular zone extends a process that reaches upward toward the pia
2. The nucleus of the cell migrates upward from the ventricular surface towrd the pial surface
3. The nucleus containing two complete copies of the genetic instructions settles back to the ventricular surface
4. The cell retracts its arm from the pial surface
5. The cell divides in two

Question 16

Wich kind of cell division predomintes the early the development of neurons?

Answer 16

Vertical cleavage

Later in development horizontal cleavage is the rule.

Question 17

Neuroblasts destined to bevome the adult cortex migrate through the subplate to form another cell layer called…?

Answer 17

cortical plate

Question 18

Explain the inside-out developement of the cortex.

Answer 18

The first cells to migrate to the cortical plate are those that form the subplate. As these differntiate intoneurons the neuroblasts destined to become layer VI cells migrate past and collect in the cortical plate. This process repeats until all layers of the cortex have differentiated. The subplate neurons then disappear.

Question 19

Name the three phases of how axons find their appropiate target

Answer 19

pathway selection, target selection and address selection

Question 20

The growing tip of a neurite is called?

Answer 20

growth cone

Question 21

What do filopodia do?

Answer 21

Probe the environment and direct the growth of the axon toward attractive cues

Question 22

synaptic rearrangement is the final step of…?

Answer 22

address selection

Question 23

Results indicate that a consequence of strong NMDA receptor activation is a strengthening of synaptic transmission…called?

Answer 23

Long-term potentiation