W4-Growth & Development of Neurons

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fastfreddy
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260900
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W4-Growth & Development of Neurons
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2014-02-09 14:34:19
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Neurons
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Growth & Development of Neurons
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  1. Humans CNS begins to develop around ___ weeks? and begins as a _____ with the forward area differentiating into the hindbrain, _____, and forebrain
    A:2  B: neural tube C. midbrain
  2. At birth the brain weighs about ___ grams?  at the end of the of the first year it was ___ grams?  and an adult brain weighs about ___ grams?
    a: 350 b: 1000 c.  1,200-1,400
  3. What are the 5 processes in the development of neurons?
    1: proliferation, Migration, differentiation, myelination, synaptogenesis
  4. Proliferation =
    production of new cells
  5. Proliferation; the stem cells lining neural tube gives rise to the primitive ____ and ___?
    These primitive/immature neurons and glia begin to migrate while the stem cells rapidly continue to produce more ____ neurons & __ cells?
    a: neurons   b: glia   c: baby  D: glia
  6. Migration = movement of ____ & ____?
    neurons  & glia
  7. Differentiation:  immature neurons develop ___ first? A neuron may grow it's axon by initially locating near the ____ and growing the axon ___ from the target cell?
    a: target  b: away
  8. Differentiation: can leave the tip of the axon ____  the target Or it may grow the axon ___ toward the target?
    a: near    b: down
  9. Myelination is the process by which glial cell form ___? Myelination continues for ___? think how long it takes for your legs to finish growing...
    a: myelin    b: decades
  10. A mixture of proteins and phospholipids forming a whitish insulating sheath around many nerve fibers, increasing the speed at which impulses are conducted =
    Myelin
  11. Synaptogenesis =?  and begins before birth, and continues through ___? and slows with age as do formation of new ____ branches?
    a: formation of synapses   b: life

    c:  dendritic
  12. Most neurons develop by _____?
    infancy  *very few grow afterwards
  13. WE continue to have __ cells in the ___  receptors?
    a: stem  b: olfactory
  14. Birds develop ___  each spring for singing?
    new neurons
  15. As neurons grow older, they are less capable of changing _____  shape and making new ____?
    a: dendtrites   b: connections
  16. Possible stem cells in the ___ will stay to help keep this area able to learn new tasks
    hippocampus
  17. It appears that in mammals, at maturity, the ____ cortex forms few or no new neurons under normal circumstances
    Cerebral
  18. Carbon 14 study showed that c-14 peaked in 1963 has been ____ since that time?
    decreasing
  19. Cells keep their DNA until ___?
    death
  20. Skin cells change every ___? so the c-14 level in skin cell DNA is the same as the year you're testing
    year
  21. Heart cells aren't replaced (maybe 1% a year) and the C-14 level in their DNA corresponds to the ____?
    year of birth
  22. C-14 study show that levels in neurons in the cerebral cortex correspond to the year of one's __?
    a: birth
  23. Chemical (guidance cues) that proteins in the axons are attracted to, guide neural migration and are responsible for ___ getting to their target cells
    axons
  24. Axons form many connections in approximately the ____ location and dendrites(target cells) ____ synapses from many axons?
    a: correct   b: receive
  25. Over time some synapses are ___  and others are ___?
    strengthened and eliminated
  26. Neural Darwanism- synapses form with only approximate accuracy and then a selection process occurs and we ___ some & ___ some
    keep & reject
  27. When a neuron synapses onto a target cell, the target cell releases a protein called ___? that allows the neuron to survive
    Nerve Growth Factor (NGF)
  28. If the axon does not connect with the appropriate post-synaptic cell by a certain age, the neuron ____?  This self-distruction is called ___?
    A: degenerates b: apoptosis
  29. When a Neuron dies because of injury =
    Necrosis
  30. Nerv Growth factor(NGF) is a ____ found in the CNS
    a: neurotrophin * greek for nourishment
  31. Neurotrophins are a family of ___ that promote neuron survival and development.
    Belong to a class of growth factors(proteins the that signal particular cells to ___?
    a: protiens  b: survive
  32. Brain-derived neurotropic factors (BDNF) is a neurotropin necessary for the growth of ___ & ___, and formation of new ____?
    a: axons & dendtrites   B: synapses
  33. For an immature neuron to survive it needs ____ from target cells and ____ from incoming axons, so they need connections at both ends
    a: neurotrphins  b: neurotransmitters
  34. All areas of the nervous system make more neurons than needed. The developing muscle doesn't know exactly how big a muscle, ___ will be
    gland
  35. Brain areas of a period of massive cell death that is required for ______?
    natural development
  36. E.g., teens show increased activity in their frontal lobes during a time when they are losing cells in that area. * maturation of needed cells is linked to ___?
    loss of non-successfully linked cells
  37. People who are born blind have a thicker ____ than sighted people  =
    a: visual cortex   b: = ineffective "pruning"
  38. Developing brain is very sensitive to ____, ____, & infections?
    toxins, malnutrition
  39. Fetal alcohol syndrom-  alcohol crosses the placenta where it is neuro-toxic and can cause permanent damage to the__?
    CNS
  40. Effects of Fetal A-Syndrom are?
    attention deficits, cognitive impairment, memory, learning disabilities, motor problems, poor awareness, facial and heart abnormalities
  41. Fetal A-syndrom is known as the leading cause of ___ in the US and Europe.
     3 cases per 1000 births in Native americans
    cognitive impairment/mental retardation
  42. Fetal A-syndrom causes?
    impairments in learning, memory, language and attention
  43. There is no safe consumption of alcohol during pregnancy
  44. Neurons need neurtrophins from both the target cell and from ____ connecting to the neuron(a neurrotransmitter)
    axons
  45. Alcohol is a glutamate _____ and a GABA ____, so it blocks the main excitatory NT and stimulates the main inhibitory NT.
    a: antagonist/inhibitor b: agonist
  46. Alcohol causes neurons to receive less  ____ and consequently the developing neuron dies
    neurotransmitter
  47. Inhibits =
    decreases or stops completely
  48. Agonistic drugs are those that work to...
    mimic or enhance the effect of a neurotransmitter in the brain
  49. Antagonistic drugs work by blocking
    neurotransmitters in the brain
  50. Nicotine is a direct-binding agonist for Acetylcholine receptors --acts just like a neutrotransmitter, so the user feels the same effects as he or she would feel if a large amount of dopamine were to be released in the brain
    Cocaine is an example of an indirect-acting agonist in the dopamine system -and thus enhance its action
  51. Antagonistic drugs also come in two main forms. Direct-acting and indirect-acting antagonist
    Direct-acting antagonists bind to the same receptor area as neutrostransmitters and block the neutrotransmitters themselves from binding to their receptors

    B. indirect-acting antagonist drug works by inhibiting the production or release of neurotransmitters
  52. Axons and Dendrites modify their structure throughout life. 
    Gain or loss of dendritic spines relates to?
    learning
  53. Rats in an enriched environment show
    better development of dendtrites and axons
  54. Far Transfer- the idea that intellectual stimulation in one area will cause one to be more...?
    intellectually capable in other areas
  55. Far transfer is difficult to demonstrate for E.g...
    its hard to say if people who are more mentally alert don't just choose to do puzzles more often
  56. Far transfer doesn't help someone where to remember where you parked your car only that you're better at word puzzles
    also, practicing one task does not make one better at at a very similar task
  57. Best ways to maintain healthy cognitive function into old age are...
    physical activity, practice/repitition,
  58. Losing a sense does not affect other sense receptors for e.g..
    blindness does not change the touch receptors or change the receptors in the area for hearing
  59. people who lose a sense, the other senses adapt and become more ?
    enhanced and sensible
  60. In blind people, there is substantial activity in the ____ cortex when presented with either touch or auditory sensations
    occipital --- info from those senses has invaded teh visual cortex which normally only processes visual info
  61. When occipital cortex of blind and sighted people where inactivated by magnets, blind, but no sighted people, did worse at?
    identifying objects they were feeling
  62. Blind people also outperform sighted people on many verbal skills.
    is also linked to activity in the occipital cortex
  63. When a brief magnetic stimulation was applied to sighted people at the occipital cortex, they report a ?
    a flash of light, but blind people saw very little or almost nothing due to neuron damage in that area
  64. Gray matter of areas in the brain related to hand-control and vision are ____ in musicians than non-musicians
    thicker -

    also practicing a skill re-organizes the brain to maximize performance of that skill
  65. If the representation of the fingers grows from side to side without spreading out the areas representing that finger can --? overlap a
    neighbor
  66. When reorganization occurs, stimulation of one finger ___ the same ___ areas of another finger
    a: excites   b: cortical
  67. "Musicians cramp" =
    focal hand dystonia, the fingers become clumsy, tired, move involuntary
  68. Extensive reorganization at the level of the ___ and ___?
    thalumus and motor cortex
  69. Ati-saccade task =
    looking away from a powerful attention getter, almost impossible for kids age 5 & younger
  70. saccade =

    ant-saccade =
    a: voluntary eye movement

    b: voluntary movement away from normal dirrection
  71. Studies show that adolsescent brains have strong responses when anticipating rewards and ____ responses in areas ____?
    a. weak    b: responsible for inhibiting behavior
  72. In general people see decline in memory at what age?
    60
  73. with age, neurons ______ more slowly, Temporal cortex and hyppocampus becomes ____?
    a:alter synapses   b: thinner

    ** around age 30 frontal cortex begins thinning
  74. How do older brains compensate for loss of memory?
    • * both sides of the prefrontal cortex were activated and only one side for the same task were shown for adolescents...
    • * older adults use multiple parts of the brain to compesate
  75. Traumatic brain Injury also TBI
    injury to the brain by external forces, caused by direct impact or acceleration injury-movement of brain in the skull
  76. What causes damage to neurons?
    -direct crushing-shearing of axons-high concentration of glutamate transmitters
  77. TBI- Primary impact followed by a secondary injury - e.g.,
    bleeding, blood clots interrupting, inflammation, increased pressure in skull
  78. Main causes of TBI are?
    Falls, esp. ages 2-4, abuse 20%, car accidents, construction accidents, sports, fire arms, and blast injuries-1.4 million a year USA only, 50 k deaths
  79. Chronic Traumatic Encephalopathy -CTE
    A degenerative disease due to multiple concussions-"punch drunk" - early boxers in 1920's
  80. Ann McKee, MD- found a link between head trauma and long-term degenerative brain disease
    -mainly football players of young to old ages and some veterans - 80% showed CTE
  81. CTE- Atrophy of frontal and frontal Lobes
    -also of the thalamus, brainstem, substantia nigra, cerebellum-neural loss, protein deposition (Tau Protein) neurofibrially tangles and glia tangles
  82. Tau Protein  =
    "glue" that holds microtubules together, when neurons are damaged these proteins tangle - similar to alzheimers DZ
  83. 4 progressive stages of Chronic Traumatic Encephalopathy- symptoms
    • 1. headaches, confusion, poor judgement/attention
    • 2.erratic behavior, depression, memory loss
    • 3.cognitive impairment, poor executive functioning- planning & organizing
    • 4. deterioration to dementia, increased inability to walk, talk, -aggression builds up
  84. CTE - NFL players who died of multiple cuncussions
    • -Dave Duerson-suicide-stage 3 cte
    • -Junior Sau-suicide
  85. Multiple concussion within same week =
    far more dangerous than if had them independently
  86. Study for TBI in rats showed....?
    • -decreased glucose metabolism at 24 hrs (19%) in parietal lobe and hippocampus
    • -2nd tbi = 37% decrease in glucose in 24rs and 25% in 3 days
    • --** damage is additive
  87. Cerebrovascular Accident (CVA) aka "stroke"
    -interruption of normal blood flow, lacking O2
  88. 2 types of of CVA's are?
    Ischemic & hemorrhagic
  89. Ischemic CVA are caused by ?
    -blockage in a artery
  90. Hemorrhagic is caused by?
    ruptured blood vessel bleeding into brain
  91. CVA-stroke - symptoms
    • -unsteady gate, trouble speaking or understanding, paralysis of motor cortex, weakness or numbness of part the body on one side, sudden visual changes, heachache.
    • -Go to ER immediately
  92. CVA/Stroke- time is crucial for treatment
    • -get CT scan to see if it's hemorrhagic or ischemic
    • -if ISCHEMIC - RX = tissue plasminogen activator (TPA) dissolves blood clots.. the sooner the better
  93. Ischemic---> lack of blood---> lack of O2, and glucose and therefore lack ATP
    • so no Na+/K+ pump, but High levels of NA+-- neuron death---release glutamate--toxic
    • -edema increases the pressure on surrounding neurons and increases additional strokes
  94. CVA/stroke--- Which Glia cells proliferate and migrate to stroke area to help "clean up" dead cells and supply chemicals to help remaining neurons survive
    Microglia?
  95. CVA/stroke treatment
    • -cool the brain down, keeping neurons from releasing glutamate
    • -electrical stimulation,
    • -stimulant drugs, study with drugs... showed improvement once off the stimulant drugs
  96. After damage in any brain area, other areas that have lost part of their normal input become less active
    • -So you will see deficits in areas that haven't been damaged
    • -Possible treatment- stimulate the areas that have lost input but are still intact themselves
  97. Regrowth of Axons - destroyed cell bodies are not replaceable but when axons are damaged they can grow under certain circumstances
    - in the Peripheral Nervous System-if crushed, an axon can grow back following it's myelin sheath (Schwan cells.) if the axon is cut, it may or nmay not line up correctly and the axon may not follow the correct path
  98. Mammals form scars after axon damage- this provides initial support for other neurons in the area but then?
    blocks re-growth
  99. Which glial cell is responsible for most scar formation?
    Astrocytes
  100. with neuron/axon damage some of the chemicals released during damage ___?
    inhibit regrowth
  101. Regrowth of Axons?
    • -possible protein bridge for axon to travel to bypass scar
    • -injecting neurotrophins to help with growth and synapse formation
  102. What creates new synapses?
    after a target cell loses input from an axon, it secretes neurotrphins that induce other axons to form new branches(collateral sprouts)-- good or bad depending if it brings different NT's
  103. gamma-amino-butyric acid = GABA
    When brain experiences an abundance of nervous tension and stress, it can be caused by a surplus of norepinephrine or epinephrine (adrenaline). To neutralize this extra adrenaline, the brain produces neurotransmitters, one of which is GABA, that have inhibitory effects upon the nervous system.
  104. GABA is synthesized in the brain from another amino acid, glutamate and....
    functions as an inhibitory neurotransmitter – meaning that it blocks nerve impulses. In the body, GABA is concentrated in the hypothalamus plays a role in the overall functioning of the pituitary gland – which regulates growth hormone synthesis, sleep cycles, and body temperature.
  105. A simplification of GABA is this.
    • Our bodies are in a constant "on" state because of constant nerve impulses. Without GABA's causing an occasional "off" state their would be no resting state. Our metabolic rate would increase to a non-functional point.
    • In a developing brain GABA is an exicatory neurotransmitter until the glutamate synapses fully matures.
  106. Denervation Supersensitivity
    If a number of axons die, the remaining synapses become more sensitive
  107. Reorganized sensory representation/phantom limbs
    if a brain loses a set of incoming axons, e.g, an arm one would expect increased sensitivity at the target cells(denervation) and collateral sprouting by other axons that normally attached to some other target
  108. Moneky finger amputation
    the 3rd finger was cut, the cortical area that was responsive to that finger, became more responsive to fingers 2 and 4
  109. Phantom limbs sensations occur if the protein of the extrasensory cortex that had been receiving sensory input from the now missing limb,....
    reorganizes and becomes responsive to axons that have sprouted from other areas of the brain
  110. Phantom Lms: axons that carry info from other areas (shoulder), sprout new ___ and the synapse to the area of the ____
    a: axons  b: somatosensory cortex that use to receive sensory info form the hand
  111. Phantom L: now the area of the brain that use to get info from the hand get info from the___?
    shoulder
  112. Phantom-Limbs: A touch to the shoulder feels like it is coming from the ___?
    missing body part
  113. Amputees who learn to use an artificial limb generally experience ____ "phantom" sensations
    less
  114. Sensations from the area that attaches to the artificial limb, ____ the abnormal connections
    displaces = replaces
  115. Therapy after brain damage focuses on ____?
    practicing skills that may be impaired but aren't lost
  116. Broca's area is one of the main areas of the cerebral cortex responsible for producing language
    This brain area controls motor functions involved with speech production. Persons with damage to Broca's area of the brain can understand language but cannot properly form words or produce speech
  117. Wernicke's area is associated with processing and understanding language.
      • Language Comprehension
      • Semantic Processing
      • Language Recognition
  118. Therapists can help patients with damaged brain areas (PT, OT, etc..)
    the sooner you start practicing after damage the better
  119. Iron Mike webster- movie notes-- suffered multiple brain injuries... concussions and etc...
    • -pitsburg steelers- dies at 50...
    • - tazes himself to be able to sleep
    • -abused ritalin

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