Neuronal Development

Question 1

Symmetric vs asymmetric division

Answer 1

Symmetric: a single parent cell with different compositions at the top and bottom splits so that each daughter cell reflects the parent composition

Asymmetric: a single parent cell with different compositions at the top and bottom splits so that daughter cells have DIFFERENT composition than each other and the parent

Question 2

Layer formation in the cerebral cortex

Answer 2

A layer of cells from the subplate migrate up towards the cortical plate to form layer six; this happens repeatedly to form the multiple layers

Question 3

Radial glia cells

Answer 3

Type of glia that extend to form a scaffold on which neuronal progenitor cells and other glia cells can migrate (extends from ventricular zone into the pia)

Question 4

Growth cone definition and examples

Answer 4

Definition: located at the tip of neuronal progenitor cells and extend to become axon terminal of the presynaptic neuron
Examples: filopodia, lamellipodia

Question 5

3 phases of forming an axon

Answer 5

1) pathway selection: axons select a path through binding of guidance cues to the developing axon 2) target selection: growth cones select the correct target 3) address selection: axons select which cells to form a synapse with

Question 6

Characteristics of stem cells

Answer 6

1. Self renewal 2. Ability to differentiate into multiple cell types

Question 7

Stem cells in the adult brain

Answer 7

Exist in the hippocampus and subventricular zone

Neurons derived from stem cells exist in the hippocampus, olfactory bulb, and corpus collosum

Question 8

Neural stem cell pathways

Answer 8

1) glial progenitor goes to oligocyte progenitor (to become oligodendrocyte) or astrocyte progenitor (to become astrocyte)
2) neuronal progenitor is polarized to become axonal projection/growth cone

Question 9

Chemoaffinity hypothesis

Answer 9

Axons grow towards other neurons that express similar proteins to itself

Question 10

Sperrys frog experiment

Answer 10

Sperry rotated frog eyes 180 degrees to see how the severed neurons would reform. They went to their matched protein regions and the frog continued to see “upside down”

Question 11

Fasciculation

Answer 11

Mechanism that causes axons to stick together through cell adhesion molecules; example: integrin on growth cone interacts with laminin on a target cell

Question 12

Guidance cue definition and types

Answer 12

Def: molecules that guide axonal growth

Chemoattractant: attracts the growth cones (netrin)
Chemorepellent: retracts growth cones (slit)

Question 13

How to form a synapse at a neuromuscular junction?

Answer 13

Motor neuron secretes neuregulin and agrin. Agrin binds muscle specific kinases (MUSK) to cause rapsin and Ach receptors to cluster in the muscle. Calcium enter presynaptic neuron to induce cytoskeleton to become presynaptic terminal

Question 14

Synpase formation in the CNS

Answer 14

Growth cones become immature presynaptic terminals that express specific molecules (ephrin, CAM, cadherins) which recognize target postsynaptic positions to cause further specialization of those terminals into a synapse

Question 15

Characteristics of apoptosis

Answer 15

Programmed cell death, cell shrinkage, nuclear DNA fragmentation, blebbing (formation of an irregular bulge in the plasma membrane)

Question 16

Neurotrophins

Answer 16

Regulatory molecules that mediate differentiation and synaptic plasticity (mediate axonal rearrangement)

Question 17

Hebbian modification

Answer 17

Neurons with same activity arrange close together

Question 18

Neural network computer model

Answer 18

Hebbs’ memory storage model that describes how interconnected cortical neurons (cell assembly) form together so that when some are activated, all are activated.

Question 19

Cell cycle phase during decelopment

Answer 19

All cell divisions are synchronized; cells in the ventricular zone are in the M phase while cells in the marginal zone are in the S phase