Lecture 9 - Brain Development

Question 1

What is the enteric nervous system?

Question 2

What percentage of serotonin is found in the gut?

Question 3

How many neurotrasnmitters are used in the gut?

Question 4

What is considered the “second brain”?

Question 5

90% of fibres in the vagus nerve carry information from the gut to the brain. True or false?

Question 6

Is there bidirectional communication between the brain, gut, and microbiota of the gut? If so, how do they communicate?

Hint: endocrine, neurocrine, cytokine (inflammation signals).

Question 7

What does the pluripotency of neurons mean?

Question 8

What determines how a neuron will specialise?

Question 9

What is neurogenesis and when does (if at all) neurogenesis stop?

Question 10

What are glial cells and how do they aid the function of neurons and neural networks?

Hint: three key functions.

Question 11

How many main types of glial cells are there? And what are they called?

Question 12

What are the roles of astrocytes?

Question 13

What do oligodendrocytes do?

Question 14

What is myelin?

Hint: white matter.

Question 15

What do Schwann cells do?

Answer 15

Schwann cells are the only glial cells in the PNS and they act like oligodendrocytes - wrapping around the axon and producing myelin to insulate the axon.
Schwann cells also aid in the function and maintenance of neurons and axons in the PNS. As they are the only glial cell in the PNS they play multiple roles, including the role oligodendrocytes play in the CNS, which is coating axons in myelin.

Question 16

What is the only glial cell found in the PNS?

Answer 16

Schwann cells are the only glial cells found in the PNS and they can like oligodendrocytes, wrapping around the axon and producing myelin.

Question 17

What do microglia do?

Question 18

What are NG2+ cells do?

Question 19

In regards to myelination, what is one reason we may see increased capacity for attention span as we grow up?

Hint: reticular formation and frontal cortex.

Question 20

What does the increased myelination of axons linking the more primitive subcortical brain regions to the more regulatory prefrontal cortical areas as we progress through adolescence mean for emotional regulation?

Question 21

What layer of the blastocyst becomes the nervous system and how does it form the nervous system?

Answer 21

The ectoderm of the blastocyst folds and fuses and this tube of ectoderm that forms becomes the nervous system later on.

Question 22

At what month of pregnancy is the CNS developed enough to support learning?

Answer 22

6th month of pregnancy.

Question 23

What is the reason the brain forms sulci and gyri?

Answer 23

Increases surface area of the cortex.

Question 24

Can synapses only form between neurons? If not, what other cells can they form between?

Answer 24

There are also neuron-to-glial cell synapses.

Question 25

When is the peak of synaptogenesis and how many synapses are being formed per second?

Answer 25

Around 34th week or 8.5months and around 40,000 synapses are being formed per second.

Question 26

What did Austin Riesen observe in the 1950s/60s that lead him to develop an experiment where he raised chimps in the dark?
What did he observe in this experiment and what evidence did this lend to the understanding of synaptogenesis/pruning and neural apoptosis?

Answer 26

Austin Riesen observed that those who had had cataracts for their whole life that then had it removed struggled with seeing certain shapes. This made him wonder whether lack of exposure to light led to the impaired of the retina/optical nerve.
He conducted an experiment where he raised chimps in the dark and found that if they were raised in the dark past 7months of age showed significant and longterm impaired to the retina and optical nerve.
This provided evidence to the idea that varied infant experiences that engage all the senses are required for the healthy and full development of the nervous system.

Question 27

Do all areas of the brain develop at the same rate? If not, which areas develop first and why and which areas develop later and what does this allow for?

Hint: sub-cortical areas and cortical areas.

Question 28

A longitudinal study looking at brain development from age 5 to age 30 years resulted in three distinct findings in regards to white matter, grey matter, and brain volume.
What were these findings and what did they provide evidence for in regards to brain development across this time period?

Question 29

What is synaptic pruning and when does it occur to the greatest extent and why does it occur?

Question 30

What does it mean if someone is a “carrier” for a genetic disorder?

Answer 30

This means that they have one allele of the defective gene, and therefore, if the disorders is recessive, they do not have the disorder.

Question 31

Does grey matter increase especially rapidly during the early years (0-2years) as well as white matter?

Answer 31

Yes. There is a very rapid growth of grey matter in first 2 years, and begins to decrease. White matter growth increases rapidly and then continues, at a slower rate, into the twenties.

Question 32

What is synaptic pruning, what is the process of synaptic pruning, and what is the purpose of synaptic pruning?

Answer 32

Synaptic pruning is the dying of synapses that are not used, and whole neurons that are not used/stimulated.
Neurons that are not sufficiently stimulated will die via apoptosis and their synapses they have made with other neurons will also die. This is synaptic pruning.

Question 33

What does the decrease in grey matter and increase in white matter across the early years and into the twenties reflect and what does this mean for the developing brain and cognition?

Answer 33

Grey matter initially increases during gestation and early years, but then begins to decrease. This is a result of synaptic pruning. Neural pruning allows the important neural connections to function more efficiently.
White matter increases, especially rapidly in the early years and then a slower rate into the twenties. This increase reflects myelination of the neural connections as well as new connections being made between different areas of the brain, i.e learning.