Chapter 23 - wiring the brain Flashcards

1
Q

What are the five positions of cellular proliferation?

A

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 toward the pial surface; the cell’s dna is copied.
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.

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2
Q

What is the result of a cell dividing horizontally? When does it happen?

A

The daugther cell lying furthest away from the ventricular surface migrates away to take up its position in the cortex where it never divides again. The other daughter cells stays in the ventricular zone to divide more.

Happens in later development.

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3
Q

What is the result of a cell dividing vertically? When does this happen?

A

Both daughter cells remain in the ventricular zone to divide again and again.

Happens early in development.

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4
Q

What happens to notch–1 and numb transcription factors during vertical and horizontal division?

A

Vertical - notch-1 and numb are equally divided among daughters, allowing them to continue dividing.

Horizontal - Notch-1 migrates with the cell that goes to the cortex, numb remains with the cell that will divide again.

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5
Q

What type of cells make the scaffolds that neuroblasts climb up during cell migration?

A

Radial glial cells

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6
Q

What are young migrating neurons called?

A

Neuroblasts

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7
Q

In what order does the cortex build itself through cell migration?

A
  1. Subplate, cortical plate comes below
  2. Layer IV
  3. Layer V
    etc.
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8
Q

Which protein regulates the assembly of the cortex as as transcription factor?

A

Reeler

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9
Q

What order do cells of the brain differentiate?

A
  1. Neuronal differentiation
  2. Astrocyte differentiation
  3. Oligodendrocyte differentiation
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10
Q

What repels growing pyramidal cell axons and attracts apical dendrites? Where is it secreted?

A

Secreted into the marginal zone.

Semaphorin 3a

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11
Q

What causes cytoarchitectural differences in adult brain cortex?

A

The arrival of thalamic axons to the cortex.

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12
Q

What are the three phases of axon development

A
  1. Pathway selection.
  2. Target selection
  3. Address selection
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13
Q

What does the glycoprotein laminin do?

A

Axon expresses special surface molecules called intergrins that bind laminins from extracellular matrix. This promotes axonal elongtation. This can direct axonal growth.

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14
Q

What is it called where axons grow and stick together?

A

Fasciculation

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15
Q

What allows fasciculation of axons to happen?

A

Cell-adhesion molecules (CAM)

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16
Q

What type of molecule attracts a growing axon?

A

Chemoattractant. An example being netrin

17
Q

What is cell differentiation?

A

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

18
Q

What is fasciculation?

A

When axons growing together stick together and travels as a group due to cell-adhesion molecules (CAMs) on the surface binding to each other.

19
Q

What is the protein slit used for? How does robo play in?

A

It’s a chemorepellant in brain wiring. Robo is the slit receptor. Without the cell expressing robot, slit will not be active.

20
Q

To what does agrin bind in the neuromuscular junction?

A

To MuSK

21
Q

Growth cone

A

The specialized tup of a growing neurite.

22
Q

Ephrin

A

A protein secreted by neurons in many parts of the developing nervous system that helps establish topographic axonal connections.

23
Q

Trophic factor

A

Any molecule that promotes cell survival.

24
Q

Apoptosis

A

A mechanism of orderly, genetically programmed cell death.

25
Q

Hebb synapse

A

A synapse that exhibits hebbian modification.

26
Q

Hebbian modification

A

An increase in the effectiveness of a synapse caused by the simultaneous actiation of presynaptic and postsynaptic neurons. Neurons that fire togethe, grow

27
Q

Monocular deprivation

A

An experimental manipulation that deprives one eye of normal vision

28
Q

Critical period

A

A limited period of time when a particular aspect of brain development is sensitive to a change in the external environment.

29
Q

Strabismus

A

A condition in which the eyes are not perfectly aligned

30
Q

long-term potentiation

A

A long lasting enhancement of the effectiveness of synaptic transmission that follows certain types of conditioning stimulation.

31
Q

long-term depression

A

A long lasting decrease in the effectiveness of synaptic transmission that follows certain types of conditioning stimulation.

32
Q

What do we mean by saying that the cortex develops “inside out”?

A

The first cells to be generated in the neocortex arrive in the cortical plate and become layer VI neurons, followed by the layer V cells, layer IV cells, and so on. This process repeats until all layers of the cortex have differentiated. It is because of this arrangement, where the later generated cells should migrate past the earlier generated cells to reach their destinations in more superficial layers of the cortex, that cortical development is said to be inside-out.

33
Q

Extracellular matrix

A

The network of fibrous proteins deposited in the space between cells.

34
Q

Cell-adhesion molecule

A

A molecule on the cell surface that causes cells to adhere to one another

35
Q

Chemattractant

A

A diffusible molecule that acts over a distance to attract growing axons.

36
Q

What are the three major states of neuronal structure development?

A

Cell proliferation, cell migration and cell differentiation.

37
Q

What is cell proliferation?

A

The creation of new daughter cells.

38
Q

What is cell migration?

A

The moving of newly created cells to their final positions.

39
Q

What is cell differentiation?

A

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