Chapter 4

Question 1

How does new variations are introduced besides the merging of the DNA of your parents?

Answer 1

Mutations, recombinations, and microduplications of genes

Question 2

artificial selection

Answer 2

choosing individuals with desired trait and make them the parents of the next generation -> humans (breeders)

Question 3

Lamarckian evolution

Answer 3

You can influence evolution by using or failing to use your body parts (wrong theory)

Question 4

Does “evolution” mean “improvement”?

Answer 4

no, just that the fittest survive. Evolution is not goal directed. Some traits are from situation to situation more or less useful. Maybe they were useful in the past, maybe they will be useful in the future.

Question 5

Does evolution benefit the individual or the species?

Answer 5

Neither: It benefits the genes! In a sense, you don’t use your genes to reproduce yourself. Rather, your genes use you to reproduce themselves

Question 6

Many people believe the human appendix is useless.
Will it become smaller and smaller with each
generation?

Answer 6

No. Failure to need a structure does not make
it smaller in the next generation. The appendix will
shrink only if people with a gene for a smaller appendix
reproduce more successfully than other people do.

Question 7

Evolutionary psychology

Answer 7

concerns how behaviors evolved. The emphasis is on evolutionary and functional explanations

Question 8

reciprocal altruism

Answer 8

the idea that individuals help those who will return the favor. The idea is not just “you scratched my back, so I’ll scratch yours,” but also “you scratched someone else’s back, so I’ll scratch yours.” By helping others, you build a reputation for helpfulness

Question 9

controversial hypothesis for altruism: group selection

Answer 9

altruistic groups thrive better than less cooperative ones. True, but: wouldn’t an uncooperative individual within the cooperative group gain an advantage?

Question 10

What are plausible ways for possible altruistic genes to spread in a population?

Answer 10

Altruistic genes could spread because they
facilitate care for one’s kin or because they facilitate
exchanges of favors with others (reciprocal altruism).
Group selection may also work under some circum-
stances, especially if the cooperative group has some
way to punish or expel an uncooperative individual.

Question 11

what does a developing baby does first: sensing or moving?

Answer 11

moving

Question 12

Proliferation

Answer 12

is the production of new cells.

Question 13

the five different processes in the development of neurons:

Answer 13

proliferation, migration, differentiation,

myelination, and synaptogenesis

Question 14

Where and what are stem cells?

Answer 14

Everywhere, they divide and send the copy (or themselves, does not matter) where it is needed to differentiate there

Question 15

migration

Answer 15

the cells begin to move on particular positions

Question 16

differentiation

Answer 16

Changing into another cell (e.g. an axon or a dendrite)

Question 17

“While migrating, a cell can already differentiate into an axon.” True or false?

Answer 17

True, it can either migrate with its tip still migrating or pushing its tail towards its destination

Question 18

“While migrating, a cell can already develop its dendrites.” True or false?

Answer 18

False, it can already differentiate into an axon, but the dendrites develop when migration ends.

Question 19

what is myelination and where does it start?

Answer 19

the process by which glia produce the insulating fatty sheaths that accelerate transmission in many vertebrate axons. Starting in the spinal cord, then hindbrain, midbrain, and finally forebrain

Question 20

synaptogenesis

Answer 20

the formation of synapses.

Question 21

Which develops first, a neuron’s axon or its dendrites?

Answer 21

The axon forms first.

Question 22

How to test how old your cells are?

Answer 22

Checking the Carbon level. (^14)C corresponds to a certain year, e.g. skin is 1 year old, bones are 15 years old cells

Question 23

New receptor neurons form in adult rodents for which

sensory system?

Answer 23

Olfaction

Question 24

What evidence indicated that new neurons seldom
or never form in the human cerebral cortex and
olfactory bulb?

Answer 24

The (^14)C concentration in the DNA
of human neurons in the cerebral cortex and olfactory
bulbs corresponds to the level during the year the per-
son was born, indicating that all or nearly all of those
neurons are as old as the person is.

Question 25

Paul Weiss & Roger Sperry

Answer 25

Weiss thought axons of detached limbs connect at the place they are and "tune" afterwards so that they send the right information to the brain. Sperry showed in newt's that axons, while connecting are attracted by some and repelled by other chemicals and therefore connect just to specific axons

Question 26

What was Sperry’s evidence that axons grow to a | specific target instead of attaching at random?

Answer 26

If he cut a newt’s eye and inverted it, axons grew back to their original targets, even though the con- nections were inappropriate to their new positions on the eye.

Question 27

How does axons find the right location to bond and connect functional?

Answer 27

the chemical gradients steer them approximately (not accurately) to the right location, there the axons forms synapses onto different axons and receives synapses from many. The post synapse strengthens the most appropriate and eliminates others

Question 28

neural Darwinism

Answer 28

In the development of the nervous system, we start with more neurons and synapses than we can keep. Synapses form with approximate accuracy, and then a selection process keeps some and rejects others. The most successful axons and combinations survive, and the others fail.

Question 29

If axons from the retina were prevented from showing spontaneous activity during early development, what would be the probable effect on development of the thalamus?

Answer 29

The axons would attach based on a chemical gra- dient but could not fine-tune their adjustment based on experience. Therefore, the connections would be less precise.

Question 30

role of the nerve growth factor (NGF) in development of the sympathetic nervous system

Answer 30

the sympathetic nervous system forms far 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) that promotes the survival and growth of the axon. An axon that does not receive NGF degenerates, and its cell body dies.

Question 31

apoptosis and the role of NGF

Answer 31

If its axon does not make contact with an appropriate postsynaptic cell by a certain age, the neuron kills itself through a process called apoptosis a programmed mechanism of cell death. NGF cancels the program for apoptosis; it is the postsynaptic cell’s way of telling the incoming axon, “I’ll be your partner. Don’t kill yourself.”

Question 32

neurotrophin

Answer 32

E.g. nerve growth factor (NGF) a chemical that promotes the survival and activity of neurons.

Question 33

Are neurotrophins saving axons from apoptosis in the CNS or in the periphery?

Answer 33

They are essential for the survival of motor neurons in the periphery.

Question 34

What process assures that the spinal cord has the right number of axons to innervate all the muscle cells?

Answer 34

The nervous system builds far more neurons than it needs and discards through apoptosis those that do not make lasting synapses.

Question 35

``` What class of chemicals prevents apoptosis in the sympathetic nervous system? ```

Answer 35

Neurotrophins, such as nerve growth factor

Question 36

At what age does a person have the greatest number of neurons—early in life, during adolescence, or during adulthood?

Answer 36

The neuron number is greatest early in life.

Question 37

fetal alcohol syndrome, a condition marked by

Answer 37

hyperactivity, impulsiveness, difficulty main- taining attention, varying degrees of mental retardation, motor problems, heart defects, and facial abnormalities.

Question 38

Drinking during pregnancy leads to thinning of what brain area?

Answer 38

cerebral cortex

Question 39

Anesthetic drugs and anxiety-reducing drugs increase activity of GABA, decreasing brain excitation. Why would we predict that exposure to these drugs might be dangerous to the brain of a fetus?

Answer 39

Prolonged exposure to anesthetics or anxiety- reducing drugs might increase apoptosis of developing neurons. Increased GABA activity decreases excitation, and developing neurons undergo apoptosis if they do not receive enough excitation. Many studies confirm that anesthetics and anxiety-reducing drugs impair brain development in laboratory animals, although the research is less complete for humans

Question 40

In the ferret study, how did the experimenters determine that visual input to the auditory portions of the brain actually produced a visual sensation?

Answer 40

They trained the ferrets to respond to stimuli on the normal side, turning one direction in response to sounds and the other direction to lights. Then they presented light to the rewired side and saw that the ferret again turned in the direction it had associated with lights.

Question 41

Although the central structure of a dendrite becomes stable by adolescence, the peripheral branches of a dendrite

Answer 41

remain flexible throughout life

Question 42

An enriched environment promotes growth of axons and dendrites in laboratory rodents. What is known to be one mportant reason for this effect?

Answer 42

Animals in an enriched environment are more ac- tive, and their exercise enhances growth of axons and dendrites.

Question 43

Name two kinds of evidence indicating that touch information from the fingers activates the occipital cortex of people blind since birth.

Answer 43

First, brain scans indicate increased activity in the occipital cortex while blind people perform tasks such as feeling two objects and saying whether they are the same or different. Second, temporary inactiva- tion of the occipital cortex blocks blind people’s ability to perform that task, without affecting the ability of sighted people.

Question 44

Which brain area shows expanded representation of the left hand in people who began practicing stringed instruments in childhood and continued for many years?

Answer 44

``` Somatosensory cortex (postcentral gyrus) of the right hemisphere. ```

Question 45

“musician’s cramp”/ focal hand dystonia

Answer 45

stimulation on one finger excites mostly the same corti- cal areas as another finger. If you cannot clearly feel the difference between one finger and another, it is difficult to move them independently. Furthermore, the motor cortex changes also. One or more fingers may go into constant contraction.

Question 46

What change in the brain is responsible for musician’s | cramp?

Answer 46

Extensive practice of violin, piano, or other instru- ments causes expanded representation of the fingers in the somatosensory cortex, as well as displacement of representation of one or more fingers in the motor cortex. If the sensory representation of two fingers overlaps too much, the person cannot feel them sepa- rately or move them separately.

Question 47

Under what circumstances are adolescents most likely | to make an impulsive decision?

Answer 47

Adolescents are most likely to make an impulsive | decision in the presence of peer pressure.

Question 48

When 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?

Answer 48

The prefrontal cortex

Question 49

What is one way in which older adults compensate for | less efficient brain functioning?

Answer 49

Many of them compensate by activating additional | brain areas.

Question 50

closed head injury

Answer 50

a sharp blow to the head that does not puncture | the brain. In young people most common cause of brain injury

Question 51

stroke/ cerebrovascular accident

Answer 51

A common cause of brain damage, especially in older people, is temporary interruption of normal blood flow to a brain area during a stroke, also known as a cerebrovascular accident.

Question 52

ischemia

Answer 52

Common type of a stroke: Result of a blood clot or other obstruction in an artery. The neurons deprived of blood lose much of their oxygen and glucose supplies.

Question 53

hemorrhage

Answer 53

Less common type of a stroke: Result of a ruptured artery. The neurons are flooded with blood and excess oxygen, calcium, and other chemicals.

Question 54

edema

Answer 54

Result from a stroke: The accumulation of | fluid, which increases pressure on the brain and the prob ability of additional strokes

Question 55

tissue plasminogen activator (tPA)

Answer 55

medicament that help when having an ischema by breaking up the blood cloth. Makes things worse in a hemorrhage

Question 56

two ways that proved to be helpful against a stroke

Answer 56

cooling (reduces overstimulation, apoptosis, and inflammation) and cannabinoids (decrease the release of glutamate and exert anti-inflammatory effects)

Question 57

What are the two kinds of stroke, and what causes | each kind?

Answer 57

The more common form, ischemia, is the result of an occlusion of an artery. The other form, hemorrhage, is the result of a ruptured artery.

Question 58

Why is tPA not helpful in cases of hemorrhage?

Answer 58

The drug tPA breaks up blood clots, and hemorrhage results from a ruptured blood vessel, not a blood clot.

Question 59

If one of your relatives has a stroke and a well-meaning | person offers a blanket, what should you do?

Answer 59

Refuse the blanket. Recovery will be best if the stroke victim remains cold.

Question 60

Diaschisis

Answer 60

refers to the decreased activity of | surviving neurons after damage to other neurons.

Question 61

After someone has had a stroke, would it be best (if possible) to direct stimulant drugs to the cells that were damaged or somewhere else?

Answer 61

It is best to direct the amphetamine to the cells that had been receiving input from the damaged cells. Presumably, the loss of input has produced diaschisis.

Question 62

colleteral sprouting

Answer 62

A surviving axon grows a new branch to replace the synapses left vacant by a damaged axon.

Question 63

After a cell loses input from an axon, how does it react (tries to restore it)

Answer 63

secretes neurotrophins that induce other axons to form new branches, or collateral sprouts, that take over the vacant synapses

Question 64

denervation supersensitivity or receptor supersensitivity

Answer 64

If a set of synapses become inactive —perhaps because of damage elsewhere in the brain—the remaining synapses become more responsive, more easily stimulated.

Question 65

how can denervation supersensitivity cause chronic pain?

Answer 65

spinal injury damages many axons, postsynaptic neurons develop increased sensitivity to the remaining ones. Therefore, even mild input produces enhanced responses

Question 66

Is collateral sprouting a change in axons or dendritic | receptors?

Answer 66

Axons

Question 67

Is denervation supersensitivity a change in axons or | dendritic receptors?

Answer 67

Dendritic receptors

Question 68

phantom limb

Answer 68

continuing sensation of an amputated body part

Question 69

What is responsible for the phantom limb experience?

Answer 69

Synapses that used to receive input from the now amputated part become vacant. Axons representing another part of the body take over those synapses. Now stimulation of this other part activates the syn- apses associated with the amputated area, but that stimulation feels like the amputated area.

Question 70

deafferented

Answer 70

incurred damage to the sensory nerves linking a forelimb to the spinal cord, the animal no longer feels the limb, although the motor nerves still connect to the muscles. We say the limb is deafferented

Question 71

A monkey that loses sensation from one arm stops using it, but a monkey that loses sensation from both arms does use them. Why?

Answer 71

A monkey that lost sensation in one arm is ca- pable of moving it, but finds it easier to walk with the three intact limbs. When both arms lose their sensa- tions, the monkey is forced to rely on them.