Lec 2: Neural Cicruit Formation

______ has a long process from the ventricular zone to the pial end of the neuroepithelium and serves as a scaffold for migrating neurons?

Radial glia

Steps of nervous system development

1. Spefication of neural progenitor domains

2. Birth of neurons and glia

3. Migration of immature neurons and glia into final positions

4. Axonal outgrowth from neurons into target fields

5. Synapse formation

6. Refinement and apoptosis

What types of cells sense changes in light

Retinal ganglion cells

Basic pathway of visual sensation (4)

RGCs → LGN (lateral geniculate nucleus) → thalamocortical axons → cortical layer 4

Neuronal outgrowth begins (pre/post) mitosis

Post

Define polarization of a neuron

One neurite becomes an axon while the rest become dendrites

Rank the cytoskeletal components from smallest to largest

microfilaments, intermediate filaments, microtubules

Which cyoskeletal componenet is comprised of actin

Microfilaments

Cytoskeletal components:
- Filopodia:
- lamellipodia:

fingerlike extensions; wavelike extensions

Research Roger Sperry’s nobel prize winning discovery

Chemoaffinity hypotehsis

Describe the chemoaffinity hypothesis

Axon guidance must depend upon molecular cues in the tectum encoded during development

These are known as chemorepulsive cures (3)

Netrin/Slit, ephrins, semaphoring

Function of Rho GTPases

modulate actin dynamics to direct growth cone movement

What are topographic maps in neurology

Spatial representations of neural circuits

What do you call the representation of visual circuits

Retinal topography

What kinds of diseases have been liked to mutations in axon guidance cues

autism and schizophrenia

Main components of the PNS

lower motor neurons

DRG sensory neuron

What do morphogens do

Drive selective expression of transcription factors

What did scientist Viktor Hamburger discover

Neurotrophic hypothesis

Neurotrophic hypothesis

Neurons are initially overproduced then undergo a peroid of programmed cell death

In the pruning stage, what does the survival of neurons depend on

limiting levels of tropic factor

Which is more neat and orderely: apoptosis or necrosis?

apoptosis

2 families of apoptosis regulators

• Bcl2

• Caspases

What do caspases stand for

cysteine-dependent aspartate-directed proteases

2 members of Bcl2 family (and their function)

• Bax: pro-death

• Bcl-2: pro-life

The “Neurotrophic Hypothesis” is based in part on pioneering studies in chick embryos, which found that removing the limb bud led to a decrease in the number of limb-innervating sensory and motor neurons. Which of the following statements regarding this process is most accurate?

Neurons are initially overproduced and undergo apoptosis if unable to acquire limiting levels of neurotrophins in the target.

What trophic factor induces neuronal survival?

NGF (nerve growth factor)

Match each peptide with its tyrosine kinase
TrkA:
TrkB:
TrkC:

NGF; BDNF; NT3

NGF/TrkA promotes _____ neuron development

nociceptive

NT3/TrkC promotes _____ neuron development

proprioceptive