Neurodevelopment

Question 1

How many connections in the adult brain? How many neurons?

Answer 1

• 60 trillion connections

- 100 billion neurons

Question 2

How much does the brain weigh?

Answer 2

• 3 pounds

Question 3

How doe the brain structurally development?

Answer 3

• starts with neural tube within first few weeks of pregnancy

Question 4

What is grey and white matter?

Answer 4

• grey: cell bodies of neurons

- white: axons with myelin

Question 5

What is the neocortex?

Answer 5

• thin mantle that lies on the surface of the brain

- grey matter

Question 6

What are the nuclei?

Answer 6

• deep pockets of grey matter that send information to the neocortex

Question 7

When are the majority of neurons formed?

Answer 7

• first half of pregnancy

- must be produced at 200,000 neurons/minute

Question 8

When does brain development occur?

Answer 8

• from 20 days conceived to early adolescents

Question 9

How does the amount of neurons in infants compare to adults? What does this mean?

Answer 9

• twice as many neurons as adult
• twice as many connections
• means that development must include and overproduction and pruning back of neurons

Question 10

How do brain regions differ in overproduction and pruning back?

Answer 10

• pattern is the same
• timing is different
• so different peak times in different regions

Question 11

Why do cells die during development?

Answer 11

• only cells that are part of functioning networks have access to Nerve Growth Factor
• when they don’t make connections, they die off

Question 12

When does sensory/motor function begin?

Answer 12

• prenatally

Question 13

What are the two streams of thought on how the brain develops?

Answer 13

• innate: biologically predetermined
• emergent: influenced by experience
• nature AND nurture

Question 14

What is plasticity?

Answer 14

• new brain structures and functions build upon earlier developing ones
• the development of each new structure requires the interaction of genetic cues and input from the environment

Question 15

What are genes?

Answer 15

• two strands of DNA coiled together in double helix

Question 16

What do genes do?

Answer 16

• not one gene for eye colour, artistic talent, etc.
• many genes contribute to development
• provide a template for making proteins

Question 17

Which two genes work together to define basic neocortical areas?

Answer 17

• Pax6 and Emx2

Question 18

Where are Emx2 and Pax6 expressed?

Answer 18

• Emx2: high concentration in back and middle

- Pax6: high concentration in front and sides

Question 19

What levels of Emx2 and Pax6 signal cells to take on which functional roles?

Answer 19

• high Emx2 and low Pax6: vision
• high Pax6 and low Emx2: motor
• intermediate of both: touch

Question 20

What happens if Emx2 expression is lowered?

Answer 20

• expression of Pax6 moves further backward
• vision contracts
• motor and touch expand and shift backward

Question 21

What happens if Pax6 expression is lowered?

Answer 21

• brain areas shifted forward
• vision expands
• motor and touch contract

Question 22

How did the rats differ in the different environments?

Answer 22

• animals in enriched environment make more synapses and maintain over life
• for young rats and adult rats