development part 3

Question 1

Axon guidance is ______ between intermediate targets

Answer 1

dynamic

Question 2

Layered on top of _________, receptor expression can _____ in response to the environment.

Answer 2

antagonistic gradients. change. In this way axons can be attracted and repelled by the same structure.

Question 3

Normal development requires______.

Answer 3

pruning

In many developmental situations, extra cells/tissues are formed, which are pruned back during later development.

Question 4

Input neurons ______ for target neurons

Answer 4

compete.

By competing, the strongest and best placed cells survive.

Question 5

Trophic factors

Answer 5

Target neurons secrete trophic factors that help keep cells alive.

Trophic factors induce pro-survival activities,
while their absence causes pro-apoptotic activities.

The default behavior for many developing neurons is to die! These trophic factors keep them alive.

Question 6

Rita Levi-Montalcini,

Answer 6

Got her medical degree in 1936 from the University of Turin
she began working as a research assistant in neurobiology

Question 7

Why did Rita Levi-Montalcini lose her jobafter only 2 years of working?

Answer 7

Italy’s fascist regime barred Jews from
working in major professions.

Question 8

What did Rita Levi-Montalcini do after she got owned?

Answer 8

she set up a makeshift laboratory in her bedroom where she began studying the development of chicken embryos, which would later lead to her scientific breakthrough.

Question 9

What did Rita Levi-Montalcini do in 1943, when the Nazis invaded Italy?

Answer 9

She fled to Florence and lived underground, assuming false identities.

Question 10

what did Rita Levi-Montalcini discover and where?

Answer 10

By 1947, Levi-­Monalcini was based at Washington University in St Louis, Missouri, where she eventually became a full professor.

It was here that she continued her work into cell development and discovered the nerve growth factor.

Question 11

Maturation

Answer 11

Multiple axons from motor neurons can innervate a single muscle fiber.

Maturation involves pruning extra axonal projections so
there is one motor nerve per muscle fiber.

Question 12

What happens to trophic factors encountered by the axon?

Answer 12

Trophic factors encountered by the axon are transported back on the axon to the cell body.

Question 13

Muscle fiber stimulation _______ the elimination of all but
____ input.

Answer 13

accelerates.

one.

Question 14

Synapse elimination at the NMJ requires_____.

Answer 14

activity

Question 15

Blocking a small subset of post-synaptic acetylcholine
receptors leads to

Answer 15

recptor loss and axon retraction.

Question 16

What does blocking muscle activity prevent?

Answer 16

loss of excess synapses

Question 17

insufficient receptor activation in an otherwise
active neuromuscular junction leads to ______.

Answer 17

synapse pruning.

Context matters – without on-going synaptic activity,
inactive synapses are not pruned.

Question 18

cortical thickness ______ after development, while number of synapses __________.

Answer 18

doesnt change.

dramatically decreases.

Question 19

Synaptic rearrangement alters ______

Answer 19

the balance of synaptic input.

Question 20

what happens during maturation in terms of inputs and capacity?

Answer 20

During brain maturation the balance of synaptic inputs may
change, while the total synaptic capacity is unaltered. This
synaptic rearrangement requires synaptic transmission.

Question 21

molecular guidance molecules.

Answer 21

Allows for long range connections can be established without the need for synaptic activity early in development

Question 22

when does activity dependent refinement of synaptic
connections occur?

Answer 22

later in development, and through maturity.

Question 23

Retinal axons enter the LGN diffusely, but eventually what happens?

Answer 23

They segregate such that each eye targets specific structures. This requires synaptic activity, but not light

Question 24

Brain dervied Nerotropic factor (BDNF)

Answer 24

is synthesized in the cortex and its co-release with glutamate is critical for striatal neuron survival.

Question 25

Neurotrophins stimulate complex signals

Answer 25

The interaction of neurotrophins with their receptors stimulate complex intracellular signaling cascades, which are largely based regulation of transcription.

Question 26

Synaptic rearrangement can be dynamic (AGRP/POMC)

Answer 26

In response to peripheral hunger signals (e.g. leptin and ghrelin) the balance of excitatory and inhibitory synapses on AGRP/POMC neurons in the hypothalamus switches.

NPY stimulates appitite.

POMC inhibits appetite.

Question 27

“Hebbian” synapses in the LGN

Answer 27

Initially, input from each eye targets multiple layers of cells in the LGN.

Correlated firing in neurons from the same retina strengthens connections with active post-synaptic neurons, which subsequently fire.

Lack of correlated firing in non-target neurons leads to synapse loss. The net effect is segregation of synaptic inputs into their appropriate layers.

Question 28

Neural precursor cells in the ventricular zone replicate their DNA after sending a projection where?

Answer 28

towards the pial surface

Question 29

When do Neural precursors replicate?

Answer 29

They replicate their DNA while their soma moves towards the pial surface and back.

Question 30

Once replicated and back at the ventricular surface they divide _____ or _________.

Answer 30

horizontally or vertically

Question 31

how could you make a neuron grow towards cues faster?

Answer 31

Increase their expression for certain receptors.