Development And Plasticity Flashcards
When does the nervous system begin to form for an embryo>
2wks
How much does the brain weigh at birth?
350g
First year how much does brain weight
1000g
How much does the adult brain weigh
1200-1400g
Proliferation
Production of new cells/neurons in brain
migration
Movement of newly formed neurons and glia to location
T/F some neurons dont reach their location until adulthood
True
How does migration happen?
Follow chemical paths
Differentiation
Forming of axon and dendrite that gives neuron its shape
What part of the neuron grows first? When?
Axon
During migration/when it reaches target
When do dendrites develop
After axon
Where does myelination first occur
Spinal cord
Synaptogenesis? When does it occur?
Formation of synapses between neurons
Constantly forming and discarding old ones
Stem cells
Undifferentiated cells that generate daughter cells that can transform into glia or neurons
What do stem cells differentiate into?
New neurons in the hippocampus
Do mammalian cerebral cortexes form new neurons after birth?
No
How do axons reach their target areas?
Following a gradient of chemicals- more attracted to some chemicals and repelled by others
Strengthen connections with some cells and eliminate connections w others
Postsynaptic cells
What controls the formation or elimination of connections?
Inputs from incoming axons
Neural Darwinism
Initially form more connections than we need
Most successful connections survive
Nerve growth factor
Promotes survival and growth of axons
How does the brain’s system enable exact matching of number of incoming axons to number of receiving cells
Apoptosis
Neurotropin
Chemical that promotes neuron survival
Why is the visual cortex thicker on blind people?
Lack of stimuli; cannot prune out ineffective neurons
Chemical distortions in brain during development can cause
Impairment and developmental problems
Fetal alcohol syndrome
Mother drinks heavily during pregnancy
What are the dendrites like in children with fetal alcohol syndrome?
Short
What does alcohol in the fetus brain suppress and enhance?
What does this cause
Glutamate
Release of GABA
Less excitation, more apoptosis
Smoked cigarettes
Risk for ADHD
What do antidepressants during pregnancy increase the risk of
Heart problems
________ neurons transplanted to a ______ part of the cortex develop the properties of the new location
Immature
Developing
neurons transplanted at a _____ stage of development develop some new but retain some old properties
Later
How does fine-tuning work?
Dendrites continue to modify structure and connections through life time
Dendrites continually grow new spines
Rats raised in an _______ environment develop a _____ cortex and _______ dendritic branching
Enriched
Thicker
Incr
What helps expansion of neurons
Physical activity
Closed head injury
Sharp blow to head that does not puncture brain
Stroke
Temporary loss of blood flow to brain
Ischemia
Blood clot that causes neurons to lose oxygen and glucose supplu
Excitoxiticity
Neurons flooded with excess blood, calcium, oxygen, and other chemicals
Edema
Accumulation of fluid in brain resulting in increased pressure
Diaschisis
Decreased activity of surviving neurons after damage to other neurons
Cell bodies cannot be ____ but axons do _____
Replaced
Grow back
Damaged axons only regenerate ______ mm
1-2
Denerviation supersensitivity
Heightened sensitivity to neurotransmitter after the destruction of incoming axon
Phantom limb
Continuation of sensation of amputated body part
Collateral sprouts
New branches formed by other non damaged axons that attach to vacant receptors
Autism has ____ paths
Multiple
What does brain development in autistic children
Larger, but areas are under activated
Later period of degeneration
