Behavioral Neuroscience > Ch. 4: Genetics, Evolution, Development, Plasticity > Flashcards

Ch. 4: Genetics, Evolution, Development, Plasticity Flashcards

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1
Q

Mendel

A

demonstrated inheritance occurs through genes

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2
Q

Genes

A

units of heredity that maintain structural identity

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3
Q

Chromosomes

A

strands of genes that come in pairs

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4
Q

DNA: Deoxyribonucleic acid

A

composed of genes

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5
Q

Strand of DNA serves as template model for

A

ribonucleic acid (RNA) molecules, a single-strand chemical. One type of RNA molecule—messenger RNA— serves as a template for the synthesis of protein molecules.

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6
Q

DNA has 4 bases

A
  1. Adenine
  2. Guanine
  3. Cytosine
  4. Thymine
    The order of those bases determines the order of corresponding bases along an RNA molecule—adenine, guanine, cytosine, and uracil (in RNA and not DNA). The order of bases along an RNA mole- cule in turn determines the order of amino acids that compose a protein.
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7
Q

Some proteins serve as enzymes

A

catalysts that regulate chemical reactions in the body

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8
Q

Homozygous

A

same genes on your two copies of some chromosome

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9
Q

Heterozygous

A

an unmatched pair of genes

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10
Q

Dominant gene

A

shows a strong effect in either the homozygous or heterozygous condition

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11
Q

Recessive gene

A

shows its effects only in the homozygous condition

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12
Q

Can single gene produce particular outcome

A

No

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13
Q

Sex linked genes

A

The genes on the sex chromosomes (designated X and Y in mammals)

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14
Q

Autosomal genes

A

All other chromosomes are autosomal chromosomes and their genes are

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15
Q

You express most of your genes in certain cells and not others

A

changes in the environment can increase/decrease expression of a gene

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16
Q

RNA=

A

1 copy strand of DNA

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17
Q

Sex limited genes

A

present in both sexes but active mainly in one sex

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18
Q

Mutations

A

heritable change in a DNA molecule. Changing just one base in DNA to any of the other three types means that the mutant gene will code for a protein with a different amino acid at one location in the molecule.
Another kind of mutation is a duplication or deletion. During the process of reproduction, part of a chromosome that ordinarily appears once might instead appear twice or not at all. When this process happens to just a tiny portion of a chromosome, we call it a microduplication or microdele- tion.

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19
Q

Epigenetics

A

Changes in gene expression. Various experiences can turn a gene on or off. Epigenetic changes can be inherited for a generation or 2

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20
Q

Histones

A

Proteins that bind DNA. Histones tighten, stop expression of gene. If they relax, express gene. Adding methyl groups to a promoter turns off a gene

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21
Q

Difference b/w mutation and epigenetic change

A

A mutation is a permanent change in part of a chromosome. An epigenetic change is an increase or decrease in the activity of a gene or group of genes. Adding a methyl group turns genes off. An acetyl group loosens histone’s grip and increases gene activation

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22
Q

Heritability

A

If the variations in some characteristic depend largely on genetic differences, the characteristic has high heritability. Heritability ranges from zero, indicating no genetic contribution to the variation, to one, indicating complete control.

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23
Q

Monozygotic twins

A

Have the same genes. Not necessarily identical

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24
Q

Dizygotic twins

A

Don’t have same genes

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25
Evidence of heritability
1. Twin studies 2. Children who have been adopted 3. Candidate gene approach: Studies 1 gene 4. Genome wide association study: Studies many genes b/w 2 distinct groups
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Estimate of heritability of a trait
Specific to a pop at a given time
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PKU
genetic inability to metabolize amino acid phenylalanine
28
Almost every human behavior
Has some degree of heritability
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Evolution
Change over generations in frequencies of various genes in a pop
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artificial selection
plant and animal breeders have long understood this idea, they choose individuals with a desired trait and make them the parents of the next generation
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myth of Lamarckian evolution
use or disuse of some structure or behavior cause an evolutionary increase or decrease in that feature
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Evolution depends on
reproduction, not survival
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Evolutionary Psychology
How behaviors evolved
34
Kin selection
selection for a gene that benefits individual’s relatives
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reciprocal altruism
Helping others with the intention of receiving help in return
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group selection
altruistic groups thrive better
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Homeobox genes
regulate expression of other genes and control start of anatomical development, like front and back directions
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Process of development
1. Fetus develops CNS at 2 weeks old 2. Dorsal surface thickens, becomes tube and makes hind, mid and forebrain 3. We start moving before receiving sensations 4. Infant brain set up to see, hear, and receive sensory info but not how to interpret info (prefrontal cortex slowest to develop)
39
proliferation
production of new cells
40
Stem cells
Cells that do not become specified for some specific function, can become something else
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When do most neurons form by
Most neurons form within first 28 weeks of gestation, process is stopped by premature birth
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Early on primitive cells guided by
immunoglobulins and chemokines. Deficit in these chemicals leads to impaired migration, decreased brain size and retardation
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Cell differentiates into
neuron, forms dendrites, axons and synapses (synaptogenesis, which begins long before birth but continues throughout life as neurons discard old synapses)
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Myelination
glia produce fatty sheaths that accelerate transmission in vertebrate axons
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What brain regions can generate new neurons
Hippocampus and olfactory bulb
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Testing carbon in humans has taught us that
skin cells are produced rapidly, skeletal cells are 15 years old, hippocampus and basal ganglia (important for learning new tasks) generate new cells every year. Cortex doesn’t generate new cells
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Growing axon follows chemical path based on
what is attracted to and doesn’t follow what it repelled from, leading to its appropriate destination
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each postsynaptic cell
strengthens most appropriate synapses and eliminates others over time
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Neural darwinism
in development of nervous system, we start w/ more neurons and synapses than we can keep, and then selection process keeps some of the synapses and rejects others. Most successful survive and others fail
50
Mutations in genes are
random events, but neurotrophins steer new axonal branches and synapses in approx. right direction
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What determines how many axons survive
Muscles
52
Sympathetic nervous system first forms more neurons than it needs
When one of its neurons forms a synapse onto a muscle, that muscle delivers a protein called nerve growth factor (NGF), which promotes survival and growth of the axon
53
Axons that don't receive nerve growth factor (NGF)
Degenerate and cell bodies die
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Apoptosis
programmed mechanism of cell death. NGF cancels apoptosis
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Loss of cells in a particular brain area often indicates
Maturation
56
Nerve growth factor is a neurotrophin
a chemical that promotes survival and activity of neurons. Essential for growth of axons and dendrites, formation of new synapses, and learning
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fetal alcohol syndrome
Drinking into pregnancy can lead to thinning of cerebral cortex during adulthood
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Brain neuron must receive input from incoming axons, alcohol inhibits receptors for
glutamate, brain’s main excitatory transmitter, and enhances receptors for GABA, main inhibitory transmitter
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Sensory input instructs cortex about
how to develop
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Far transfer
Idea that learning difficult skills will translate to general increase in ability. Has weak effect
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Just as touch and sound come to activate what would be visual cortex in blind people
touch and vision come to activate what would be auditory cortex in deaf people
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Competing hypotheses
practicing a skill reorganizes brain to maximize performance of skill. Other hypothesis is that brain characteristics present from birth lead people to a profession
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proprioceptive training
bursts of vibration towards affected muscles
64
Teenage brain response to rewards is much stronger during teenage years
So risky behaviors reflects desire for excitement less than inability to inhibit impulse
65
Frontal cortex begins thinning at age
30
66
Closed head injury
injury that doesn’t puncture head
67
If a head injury causes confusion and loss of recent memory
Duration of this period is strong predictor of long term problems
68
stroke
cerebrovascular accident
69
Ischemia
Most common type of stroke. Result of blood clot/obstruction in artery
70
Hemorrhage
Less common, ruptured artery
71
Edema
Accumulation of fluid
72
Ischemia and hemorrhage
can lead to edema and dysfunction of sodium-potassium pump
73
Tissue plasminogen activator
Breaks up blood clots (P137). Only beneficial for ischemia, and can make hemorrhage worse. Hemorrhage is rare, so tPA often given at hospitals
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Diaschisis
decreased activity in surviving neurons after damage to others
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After cell loses input from an axon
it secretes neurotrophins that induce other axons to form new branches, or collateral sprouts, that take over vacant synapses (P139). If sprouting axons convey similar info as previous axons depends on their particular function
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Denervation supersensitivity; receptor supersensitivity
When one set of synapses strengthen, the others weaken (and vice versa). Helps compensate for decreased input. Can strengthen desirable and undesirable connections, which can lead to things like chronic pain
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If brain loses incoming axons
we can expect denervation supersensitivity, collateral sprouting, or both. Result is either increased response to a synapse that previously produced little effect, or response to an axon that previously didn’t attach at all
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Phantom limb
Brain areas that start as particular body part continue to receive input even if body part is no longer there. Example: if axons representing face come to activate cortical area previously devoted to an amputated hand, touch on face produces facial sensation and sensation in phantom hand
79
Much recovery from brain damage depends on
learning to make better use of the abilities you were spared
80
deaferrented limb
Lost afferent sensory input
Behavioral Neuroscience
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