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Biopsychology > Chapter 4: Brain Development, Damage & Neuroplasticity > Flashcards

Chapter 4: Brain Development, Damage & Neuroplasticity Flashcards

1
Q

what factors does brain development depend on

A
  1. Maturation
  2. learning
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2
Q

the human nervous system starts developing during

A

it forms when the embryo is approximately 2 weeks old
the dorsal surface thickness and different parts like the midbrain, forebrain, and hindbrain start forming

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3
Q

Cerebrospinal fluid

A

It is a fluid that exists in the central canal of the spinal fluid and the ventricles of the brain provide nourishment and removes waste

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4
Q

Brain weight

A

just born: 350g
1 year: 1000g
adult human brain weight: 1200 to 1400g

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5
Q

process of the development of neurons

A
  1. proliferation
  2. migration
  3. differentiation
  4. myelination
  5. synaptogenesis
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6
Q

Proliferation: development of neurons

A

is the production of new cells\ neurons in the brain in the early stages of life
after the production, some cells become stem cells that continue to divide and others remain where they are or become neurons or glia that migrate to other locations.

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7
Q

Migration: development of neurons

A

the movement of newly formed neurons and glia to their eventual location some don’t reach their location until adulthood chemicals like immunoglobulin and chemokines guide neuron migration

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8
Q

Differentiation: development of neurons

A

is the forming of axons and dendrites that give the neuron its distinctive shape the axon forms during the migration or when it reaches its destination and it is followed by the development of dendrites

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9
Q

Myelination: development of neurons

A

the process where glia produce the fatty sheet that covers the axons of some neurons

myeline protects the neuron and speeds up the transmission of impulses myelination first occurs in the spinal cord and then the hindbrain and then the midbrain and then the forebrain it occurs gradually

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10
Q

Synaptogenesis: development of the neuron

A

The final stage of neural development –
the formation of the synapses between
neurons
– Occurs throughout life as neurons are
constantly forming new connections and
discarding old ones
– Slows significantly later in the lifetime

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11
Q

what is life span of new neurons

A

it was believed in the past that no new neurons were formed after the early stages but later research showed otherwise

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12
Q

Stem cells

A

Stem cells: undifferentiated cells found in the interior of the brain that generates “daughter cells” that can transform into glia or neurons

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13
Q

how often do olfactory receptors replace dying ones

A

New olfactory receptors also continually replace dying ones

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14
Q

where does the development of neurons occur in brain regions

A

Development of new neurons also occurs in other brain regions
Example: songbirds have a steady replacement of new neurons in the singing area of the brain
* Stem cells differentiate into new neurons in the adult hippocampus of mammals and facilitate learning

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15
Q

Life Span of Neurons: skin cells

A

Different cells have a different average life
spans
* Skin cells are the newest; most are under
a year old

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16
Q

Life Span of Neurons: Heart cells

A
  • Heart cells, on the other hand, tend to be
    as old as the person
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17
Q

Life Span of Neurons: mammalian cerebral cortex

A
  • Mammalian cerebral cortexes form few or
    no new neurons after birth
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18
Q

What is Pathfinding by Axons

A

Axons must travel great distances across
the brain to form the correct connections

it is the process by which neurons send out axons to reach their correct targets.

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19
Q

How do axons get to their targeted area

A

to reach their correct targets. Axons often follow very precise paths in the nervous system following the chemical trail to reach their appropriate target.

Growing axons reach their target area by
following a gradient of chemicals in which
they are attracted by some chemicals and
repelled by others

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20
Q

Competition among axons as a general principle

A

When axons initially reach their targets, they form synapses with several cells
* Postsynaptic cells strengthen the connection with some cells and eliminate connections with others

The formation or elimination of these connections depend on the pattern of input from incoming axons

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21
Q

Neural Darwinism

A

Some theorists refer to the idea of the selection process of neural connections as neural Darwinism

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22
Q

synaptic connections competition

A

In this competition among synaptic connections, we initially form more connections than we need

The most successful axon connections and combinations survive while the others fail to sustain active synapses

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23
Q

Determinants of Neuronal Survival

A

chemicals called neurotrophins such as NGF are responsible for the survival of the neurons

Nerve growth factor (NGF) is a type of protein released by muscles that promote the survival and growth of axons

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24
Q

Neurotrophins

A

Chemicals that promote the survival and
activity of neurons (i.e., NGF)

Axons that are not exposed to neurotrophins
after making connections undergo apoptosis –
a preprogrammed mechanism of cell death

– Therefore, the healthy adult nervous system
contains no neurons that failed to make
appropriate connection

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25
Q

What happens if axons are not exposed to neuro tropins

A

Axons that are not exposed to neurotrophins after making connections undergo apoptosis –a preprogrammed mechanism of cell death

Therefore, the healthy adult nervous system contains no neurons that failed to make the appropriate connection

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26
Q

apoptosis

A

Apoptosis is a form of programmed cell death that occurs in multicellular organisms.

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27
Q

Neuronal Death and its benefits

A

The elimination of massive cell death is part of normal development and maturation

After maturity, the apoptotic mechanisms become dormant

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28
Q

describe how is brain vulnerable during the early stages of development

A

The early stages of brain development are critical for normal development later in life

A mutation in one gene can lead to many defects

Chemical distortions in the brain during early development can cause significant impairment and developmental problems

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29
Q

what is Fetal Alcohol Syndrome

A

A condition that children are born with if the mother drinks heavily during pregnancy
and it causes to the child do the following

30
Q

what are the effects of fetal Alcohol Syndrome on children

A

it causes to the child do the following

Hyperactivity and impulsiveness
– Difficulty maintaining attention
– Varying degrees of mental retardation
– Motor problems and heart defects
– Facial abnormalities

31
Q

How are the neurons of children who are born with fetal alcohol syndrome different?

A

The dendrites of children born with fetal alcohol syndrome are short with few branches
* Exposure to alcohol in the fetus brain
suppresses glutamate and enhances the
release of GABA
* Many neurons consequently receive less
excitation and exposure to neurotrophins
than usual and undergo apoptosis

32
Q

How are the neurons of children who are born with fetal alcohol syndrome different?

A

The dendrites of children born with fetal alcohol syndrome are short with few branches
* Exposure to alcohol in the fetus brain
suppresses glutamate and enhances the
release of GABA
* Many neurons consequently receive less
excitation and exposure to neurotrophins
than usual and undergo apoptosis

33
Q

explain how fetal alcohol syndrome affects neurons: the process

A

Exposure to alcohol in the fetus’s brain suppresses glutamate and enhances the release of GABA

Many neurons consequently receive less excitation and exposure to neurotrophins than usual and undergo apoptosis

34
Q

explain how neurons differ according to their location

A

Neurons in different parts of the brain differ from one another in their shape and chemical components

– Immature neurons transplanted to a
developing part of the cortex develop the
properties of the new location
– Neurons transplanted at a later stage of
development develop some new properties
but retain some old properties
* Example: ferret experimen

35
Q

what happens if the immature neuron is transplanter in a new location: early stages

A

Immature neurons transplanted to a developing part of the cortex develop the properties of the new location

36
Q

what happens if the neuron is transplanter in a new location: later stages

A

Neurons transplanted at a later stage of development develop some new properties but retain some old properties

Example: ferret experiment

37
Q

Brain Adaptations> deaf people

A

People who are deaf from an early age become more responsive to touch and vision.

Touch and vision come to activate what would be the auditory cortex in deaf people

38
Q

Effects of Special Experiences> blind people how their brains adapt

A

Blind people improve their attention to touch and sound, based on practice

Touch information activated this occipital cortex area, which is ordinarily devoted to vision alone

  • The occipital lobe is normally dedicated to processing visual information and adapts to also, process tactile and verbal information
39
Q

differences between the brains of musicians and non-musician

A

MRI studies reveal the following: The temporal lobe of professional musicians in the right hemisphere is 30% larger than
non-musicians

Thicker gray matter in the part of the brain responsible for hand control and vision of professional keyboard players

Results suggest that practicing a skill reorganizes the brain to maximize the performance of that skill

40
Q

adulthood experiences affect on the brain

A

Adult experiences can also modify the brain anatomy however research is needed to determine if the changes can be observed by fMRI

41
Q

what happens when Brain Reorganization Goes Too Far?

A

The fingers of musicians who practice extensively become clumsy, fatigue easily, and make involuntary movements

This condition is a result of the extensive reorganization of the sensory thalamus and cortex so that touch responses to one finger overlap those of another

42
Q

Brain Development and Behavioral Development> adolescents

A

Adolescents tend to be more impulsive than adults

Adolescents are not equally impulsive in
all situations

The prefrontal cortex of adolescents is
relatively inactive in certain situations, but
this may or may not be the cause of
impulsivity

43
Q

When do people claim that adolescents make risky decisions because of a lack of inhibition, which brain area do they point to as being responsible for inhibition?

A

The prefrontal cortex of adolescents is relatively inactive in certain situations, but this may or may not be the cause of impulsivity

44
Q

how being older compensates for neural loss?

A

Some neurons lose their synapses, and the remaining synapses change more slowly than before in response to experiences Brain structures begin to lose volume

Older people have a greater base of knowledge and experience, and many find ways to compensate for losses

45
Q

Plasticity

A

The brain’s special capacity for change

46
Q

Plasticity after Brain Damage

A

Almost all survivors of brain damage show behavioral recovery to some degree Some recovery relies on the growth of new
branches of axons and dendrites.

Functional plasticity refers to the brain’s ability to heal itself after injury. To achieve this, healthy regions of the brain adapt to take over certain functions that the damaged parts of the brain used to perform.

47
Q

how does recovery take place after brain damage

A

Some of the mechanisms of recovery include those similar to the mechanisms of brain development such as the new branching of axons and dendrites

48
Q

Possible causes of brain damage

A

Tumors
– Infections
– Exposure to toxic substances or radiation
– Degenerative diseases
– Closed head injuries

49
Q

what is a closed head injury

A

refers to a sharp blow to the head that does not puncture the
brain

50
Q

what is a stroke or cerebrovascular accident

A

is a temporary loss of blood flow to the brain

A common cause of brain damage in elderly

51
Q

what is a common cause of brain dame in elderly and young adults?

A

A common cause of brain damage in the elderly is a stroke
closed head injury is the main cause of brain damage in young adults

52
Q

Types of Strokes

A

Ischemia
Hemorrhage

53
Q

apoptosis

A

a preprogrammed mechanism of cell death

54
Q

what happens if the brain of a fetus was exposed to an alcohol

A

Exposure to alcohol in the fetus’s brain suppresses glutamate and enhances the release of GABA

Many neurons consequently receive less excitation and exposure to neurotrophins than usual and undergo apoptosis

55
Q

Effects of Ischemia and hemorrhage strokes

A

they cause Edema: the accumulation of fluid in the brain resulting in increased pressure on the brain and increasing the probability of further strokes

Disruption of the sodium-potassium pump leading to the accumulation of sodium ions inside neurons

56
Q

Effects of Ischemia and hemorrhage strokes 2

A
  • The overstimulation of neurons leads to
    sodium and other ions entering the neuron
    in excessive amounts
  • Excess positive ions in the neuron block
    metabolism in the mitochondria and kill the
    neuro
57
Q

Treatments of stroke

A

A drug called tissue plasminogen activator (tPA) breaks up blood clots and can reduce the effects of ischemic strokes

Research has begun to attempt to save neurons from death by blocking:
– Glutamate synapses
– Calcium entry

Also cooling the brain helps with after-ischemia it prevents the brain from overstimulation apoptosis and inflammation

and the Cannabinoids have been shown to minimize cell loss after brain stroke.

58
Q

Later Mechanisms of Recovery from Brain Damage

A

after a brain damage is survived areas reorganize or increase their activity

as well as stimulate drugs are used to stimulate activity in
healthy regions of the brain after a stroke

59
Q

Diaschisis

A

decreased activity of surviving neurons after damage to other neurons

Because activity in one area stimulates other areas, damage to the brain disrupts patterns of normal stimulation

60
Q

regeneration of cell bodies after they die: how does that happen

A

Destroyed cell bodies cannot be replaced, but damaged axons do grow back under certain circumstances

If an axon in the peripheral nervous system is crushed, it follows its myelin sheath back to the target and grows back toward the
periphery at a rate of about 1 mm per day

61
Q

Regrowth of Axons: what is the process

A

Damaged axons do not readily regenerate in a mature mammalian brain or spinal cord

– Scar tissue makes a mechanical barrier to
axon growth
– Neurons on the two sides of the cut pull apart
– Glia cells that react to CNS damage release
chemicals that inhibit axon growth

62
Q

Axon Sprouting

A

Collateral sprouts are new branches formed by other non-damaged axons that attach to vacant receptors

  • Cells that have lost their source of innervation releases neurotrophins that induce axons to form collateral sprouts
  • Over several months, the sprouts fill in most vacated synapses and can be useful, neutral, or harmful
63
Q

What is a phantom limb

A

the continuation of the sensation of an amputated body part

a phantom limb can lead to the feeling of sensations in the amputated part of the body when other parts of the body are
stimulated

64
Q

what helps with phantom limb

A

Use of an artificial limb can reduce the likelihood of experiencing phantom limb

65
Q

Deafferentated limb

A

limbs that have lost their afferent sensory input

Can still be used but are often not because
use of other mechanisms to carry out the
behavior is easier

– Has led to the development of therapy techniques to improve the functioning of the brain damaged people

66
Q

What happens when neurons in the brain die

A

you can’t regenerate neurons but you can regenerate the growth of axons and dendrites

67
Q

What is Denervation supersensitivity

A

is the heightened sensitivity to a transmitter after the destruction of an incoming axon it can result to a chronic pain

68
Q

What chemicals help the migration process

A

Immunoglobulins and chemokines

69
Q

What is the function of myleine sheet?

A

myleine speeds up the transmission of neural impulses

70
Q

what is the life span of neurons

A
71
Q

what is life span of new neurons

A

it was believed in the past that no new neurons were formed after the early stages but later research showed otherwise

Biopsychology (7 decks)

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