Ch5-Dev & Plasticity of the Brain

Question 1

Human central nervous system begins to form when the ______ is ____ old.

Answer 1

embryo (0-10weeks)

2 weeks

Question 2

What are the 5 stages of growth and development of neurons?

Answer 2

proliferation
migration
differentiation
myelination
synaptogenesis

Question 3

responsible for the production of new cells (stage 1 of growth & dev of neurons)

Answer 3

proliferation

Question 4

responsible for the movement of cells after they have differentiated as neurons or glia (stage 2 of growth & dev of neurons)

Answer 4

migration

Question 5

the process whereby neuron forms its axon and dendrites (stage 3 of growth & dev of neurons)

Answer 5

differentiation

Question 6

the process by which glia produce insulating fatty sheaths that accelerate transmission (stage 4 of growth & dev of neurons)

Answer 6

myelination

Question 7

responsible for the formation of synapses [neurons separate] (stage 5 of growth & dev of neurons)

Answer 7

synaptogenesis

Question 8

Roger Sperry discovered what when studying newts?

Answer 8

axons find their targets by following chemical pathways; it is attracted by some pathways and repelled by others

Question 9

as the nervous system develops, we start with more neurons and synapses than we can keep
[some synapses are strengthened while others are eliminated]

Answer 9

Neural Darwinism

Question 10

Levi-Montalcini discovered ______

Answer 10

muscles do not determine how many axons form; they determine how many survive

Question 11

a neuron’s suicide program: if its axon does not make contact with an appropriate postsynaptic cell by a certain age, the neuron will kill itself
[programed mechanism of cell death]

Answer 11

apoptosis

Question 12

why does the brain overproduce neurons, then apply apoptosis?

Answer 12

this enables the CNS to match the number of incoming axons to the number of receiving cells

Question 13

chemical that promotes survival & activity of neurons

Answer 13

neurotrophin

Question 14

what would happen if apoptosis was interrupted?

Answer 14

the brain would keep growing

Question 15

name 2 types of neurotrophins

Answer 15

nerve growth factor [ngf]

brain-derived neurotrophic factor [bdnf]

Question 16

what is the most abundant neurotrophin in adult CNS?

Answer 16

brain-derived neurotrophic factor [bdnf]

Question 17

when a neuron forms synapse onto a muscle, the muscle delivers a protein called ______.
[promotes survival & growth of the axon]

Answer 17

nerve growth factor [ngf]

Question 18

when does apoptotic mechanisms become dormant, except under traumatic conditions [ex) stroke]?

Answer 18

after maturity

Question 19

what can affect the early stages of brain development?

Answer 19

malnutrition
toxic chemicals
infections

Question 20

condition marked by hyperactivity, impulsiveness, difficulty maintaining attention, varying degrees of mental retardation, motor problems, heart defects, & facial abnormalities {caused by the mother consuming large quantities of alcohol before birth]

Answer 20

fetal alcohol syndrome

Question 21

how do neurons in different parts of the brain differ?

Answer 21

in their shape & chemical components

Question 22

how does a neuron decide which type of neurons it’s going to be?

Answer 22

• immature neurons experimentally transplanted from one part of the developing cortex to another develop the properties characteristic of their new location
• neurons transplanted at slightly later stage develop some new properties while retaining some old ones

Question 23

axons & dendrites continue to modify their structure throughout life; what is the implication of this?

Answer 23

indicates new connections (learning) and the turnover of synapses

Question 24

Neuronal changes are guided by experience; rat in enriched environment vs deprived environment?

Answer 24

enriched = more dendritic branches
deprived = less dendritic branches

Question 25

neurons become more _____ and more _____ to stimuli that have been important or meaningful in the past

Answer 25

responsive; finely tuned

Question 26

What happens to the brain if a sensory system is impaired?

Answer 26

the part of the brain that would normally aid that sensory system aids a different sensory system to compensate
[losing a sense does not affect sense receptors of other sense organs; it increases attention to other sense organs, which causes the brain to adapt to that attention]

Question 27

2 hypotheses of musicians

Answer 27

1) practicing a skill reorganizes the brain to maximize performance of that skill
2) people who already had certain cognitive skills & brain features are more likely than others to become musicians

Question 28

• cortical areas map an overlap of 2 fingers
• result of extensive reorganization of sensory thalamus & cortex
• touch responses on one finger overlap to another finger

Answer 28

focal hand dystonia

musician’s cramp, writer’s cramp

Question 29

voluntary movement away from normal direction (children under 7 do not have enough control to complete this task)

Answer 29

antisaccade task

Question 30

adolescents have a tendency to discount the future and be impulsive this is due to……

Answer 30

their brains anticipating rewards and being unable to inhibit behaviors

Question 31

What happens to the brain after age 60?

Answer 31

• neurons alter synapses more slowly
• thickness of temporal cortex shrinks
• volume of hippocampus gradually declines
• cerebral cortex begins to thin at age 30

Question 32

major cause of brain injury in young adults

Answer 32

closed head injury [sharp blow to head that does not puncture brain

Question 33

temporary loss of blood flow to a brain area (common cause of brain injury in elderly)

Answer 33

stroke (cerebrovascular accident)

Question 34

2 types of stroke

Answer 34

ischemia & hemorrhage

Question 35

stroke that is the result of blood clot or other obstruction in artery; neurons are deprived of blood & lose much of their oxygen & glucose supplies

Answer 35

ischemia

Question 36

stroke that is the result of a ruptured artery; neurons are flooded with blood & excess oxygen, calcium, & other chemicals

Answer 36

hemorrhage

Question 37

stroke causes _______, an accumulation of fluid, which increases pressure on brain & probability of additional strokes

Answer 37

edema

Question 38

ischemia & hemorrhage impair _____

Answer 38

the sodium-potassium pump
[ch5 pt2] (causes overstimulation of neurons, leading to excess positive ions blocking metabolism in mitochondria and killing the neurons)

Question 39

best immediate treatment for stroke (since most common type is ischemia)

Answer 39

tpa=tissue plasminogen activator - breaks up blood clots

Question 40

decreased activity of surviving neurons after damage to other neurons

Answer 40

diaschisis

Question 41

although a destroyed cell body cannot be replaced, damaged axons can _______ under certain circumstances

Answer 41

grow back

Question 42

after loss of a set of axons, cells that lost their source of innervation react by secreting neurotrophins to induce other axons to form branches called _____

Answer 42

collateral sprouts

Question 43

heightened sensitivity to a neurotransmitter after the destruction of an incoming axon; helps compensate for decreased input

Answer 43

denervation supersensitivity

Question 44

heightened sensitivity as a result of inactivity by an incoming axon

Answer 44

disuse supersensitivity

Question 45

continuing sensation of an amputated body part; can range from tingling to intense pain

Answer 45

phantom limb

[this is due to the reorganization of cells in the cortex]

Question 46

a limb that has lost its afferent [sensory] input

Answer 46

deafferented limbs [is still usable but more difficult]