Neurodevelopment Flashcards
How many connections in the adult brain? How many neurons?
- 60 trillion connections
- 100 billion neurons
How much does the brain weigh?
- 3 pounds
How doe the brain structurally development?
- starts with neural tube within first few weeks of pregnancy
What is grey and white matter?
- grey: cell bodies of neurons
- white: axons with myelin
What is the neocortex?
- thin mantle that lies on the surface of the brain
- grey matter
What are the nuclei?
- deep pockets of grey matter that send information to the neocortex
When are the majority of neurons formed?
- first half of pregnancy
- must be produced at 200,000 neurons/minute
When does brain development occur?
- from 20 days conceived to early adolescents
How does the amount of neurons in infants compare to adults? What does this mean?
- twice as many neurons as adult
- twice as many connections
- means that development must include and overproduction and pruning back of neurons
How do brain regions differ in overproduction and pruning back?
- pattern is the same
- timing is different
- so different peak times in different regions
Why do cells die during development?
- only cells that are part of functioning networks have access to Nerve Growth Factor
- when they don’t make connections, they die off
When does sensory/motor function begin?
- prenatally
What are the two streams of thought on how the brain develops?
- innate: biologically predetermined
- emergent: influenced by experience
- nature AND nurture
What is plasticity?
- 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
What are genes?
- two strands of DNA coiled together in double helix
What do genes do?
- not one gene for eye colour, artistic talent, etc.
- many genes contribute to development
- provide a template for making proteins
Which two genes work together to define basic neocortical areas?
- Pax6 and Emx2
Where are Emx2 and Pax6 expressed?
- Emx2: high concentration in back and middle
- Pax6: high concentration in front and sides
What levels of Emx2 and Pax6 signal cells to take on which functional roles?
- high Emx2 and low Pax6: vision
- high Pax6 and low Emx2: motor
- intermediate of both: touch
What happens if Emx2 expression is lowered?
- expression of Pax6 moves further backward
- vision contracts
- motor and touch expand and shift backward
What happens if Pax6 expression is lowered?
- brain areas shifted forward
- vision expands
- motor and touch contract
How did the rats differ in the different environments?
- animals in enriched environment make more synapses and maintain over life
- for young rats and adult rats
