Psych 261 Midterm2 Ch4

Front 1

What is proliferation?

Back 1

The production of new cells

Front 2

What are stem cells?

Back 2

Cells that are continuing to divide

Front 3

What is one major difference between human brains and chimpanzee brains?

Back 3

Human neurons continue to proliferate longer.

Front 4

What chemicals guide neuron migration?

Back 4

Immunoglobulins and chemokines

Front 5

What happens if there is a deficit in immunoglobulins and chemokines?

Back 5

Impaired migration, decreased brain size, decreased axon growth, and mental retardation.

Front 6

What is neuron differentiation?

Back 6

Forming its axon and dendrites

Front 7

Which part of the neuron develops first?

Back 7

The axon

Front 8

When do dendrites begin to form?

Back 8

After the migrating neuron has reached its destination

Front 9

What is myelination? Is it a slow or fast process?

Back 9

When glia produce the insulating fatty sheaths that accelerate transmission in many vertebrate axons. It is a slow process.

Front 10

what is synaptogenesis?

Back 10

The formation of the synapses.

Front 11

What are some exceptions to the belief that the brain could not develop new neurons?

Back 11

1) The olfactory receptors - because they are exposed to the outside world and its toxic chemicals.

2) Stem cells in the nose - periodically divide with one cell remaining immature while the other differentiates to replace a dying olfactory receptor

3)The hippocampus - new supply of neurons keeps it "young" to learn new tasks. Blocking the formation of new neurons impairs new memories.

Front 12

What is one way to test for newly formed neurons?

Back 12

Using measurements of a radioactive isotope of carbon, carbon14.

Front 13

Which idea did Paul Weiss dismiss when he did his experiment with the graft of the frog leg?

Back 13

That each axon would find its way to the correct muscle in the extra limb. Later evidence supports this statement.

Front 14

How does an axon find its target?

Back 14

A growing axon follows a path of cell surface molecules, attracted by some chemicals and repelled by others, in a process that steers the axon in the correct direction. They follow a gradient of chemicals.

Eg. The axons with the lowest concentration connect to the tectal cells with the lowest concentration

Front 15

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

Back 15

If he cut a newt's eye and inverted it, axons grew back to their original targets, even though the connections were inappropriate to their new positions on the eye

Front 16

What is neural Darwinism?

Back 16

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.

Front 17

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

Back 17

The axons would attach based on a chemical gradient but could not fine-tune their adjustment based on experience. Connections would be less precise.

Front 18

What is the nerve growth factor?

Back 18

A protein delivered by the muscle when a neuron forms a synapse on it, that promotes the survival and growth of the axon.

Front 19

What happens if an axon does not receive NGF?

Back 19

The axon degenerates and its cell body dies.

Front 20

What is apoptosis?

Back 20

The process by which a neuron kills itself if its axon does not make contact with an appropriate postsynaptic cell by a certain age.

Front 21

NGF is a neurotrophin. What does that mean?

Back 21

A chemical that promotes the survival and activity of neurons. Essential for growth of axons and dendrites, formation of new synapses, and learning.

Front 22

Although neurotrophins are essential to the survival of motor neurons in the periphery, what neurons are they not responsible for the survival of?

Back 22

Neurons within the brain.

Front 23

What is the purpose of homeobox genes?

Back 23

They regulate the expression of other genes and control the start of anatomical development, including such matters as which end is the front and which is the rear.

Front 24

What is fetal alcohol syndrome?

Back 24

A condition marked by hyperactivity, impulsiveness, difficulty maintaining attention, varying degrees of mental retardation, motor problems, heart defects, and facial abnormalities.

Front 25

How does alcohol damage the brain?

Back 25

Interferes with neuron proliferation, impairs neuron migration and differentiation, and impairs synaptic transmission.

Front 26

How does alcohol kill neurons?

Back 26

1) Alcohol inhibits receptors for glutamate, the brain's main excitatory transmitter, and enhances receptors for GABA, the main inhibitor. Because of the decrease in net excitation, many neurons undergo apoptosis.

2) Further harm occurs because neurons try to compensate by building more glutamate in response to being inhibited, which brings excess Na and Ca into the cell and poisoning the mitochondria once the alcohol leaves, which leads to increased cell death.

Front 27

How does a stimulating environment affect neuronal changes? (Rats)

Back 27

Developed a thicker cortex, more dendritic branching, and improved learning.

Front 28

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

Back 28

Somatosensory cortex (postcentral gyrus) of the right hemisphere.

Front 29

Give an example of when the expansion of a relevant brain area is not always a good thing?

Back 29

When people play instruments for a long time, the representation of the fingers in the somatosensory cortex could spread out to have each finger overlap its neighbour. It would be hard to clearly feel the difference between one finger and another, therefore, it is more difficult to move them independently.

Front 30

What is focal hand dystonia?

Back 30

"Musician's cramp". One or more fingers may go into constant contraction.

Front 31

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

Back 31

In the presence of peer pressure.

Front 32

Why do old people's memory and reasoning begin to fade?

Back 32

Many neurons lose some of their synapses and the remaining synapses change more slow than before in response to experiences. Also, the prefrontal cortex becomes less able to maintain a high level of firing while storing a working memory.

Front 33

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

Back 33

Many of them compensate by activating additional brain areas.

Front 34

What is a closed head injury?

Back 34

A sharp blow to the head that does not puncture the brain.

Front 35

What are causes of damage after a closed head injury?

Back 35

1) The rotational forces that drive brain tissue against the inside of the skull.

2) Blood clots that interrupt blood flow to the brain.

Front 36

What is a stroke?

Back 36

Temporary interruption of normal blood flow to a brain area.

Front 37

What is ischemia?

Back 37

The result of a blood clot or other obstruction in an artery.

Front 38

What is a hemorrhage?

Back 38

The result of a ruptured artery.

Front 39

What happens with the neurons in ischemia and what happens to the neurons in a hemorrhage?

Back 39

In ischemia, the neurons deprived of blood lose much of their oxygen and glucose supplies.

In a hemorrhage, they are flooded with blood and excess oxygen, calcium, and other chemicals.

Front 40

What is an edema?

Back 40

The accumulation of fluid, which increases pressure on the brain and the probability of additional strokes.

Front 41

what do both ischemia and hemorrhage impair?

Back 41

The sodium-potassium pump, leading to an accumulation of sodium inside neurons.

Front 42

What does a combination of an edema and excess sodium provoke?

Back 42

Excess release of the transmitter glutamate, which damages both neurons and synapses.

Front 43

What does the drug tissue plasminogen activator (tPA) do?

Back 43

It breaks up blood clots.

Front 44

What is diaschisis?

Back 44

Refers to the decreased activity of surviving neurons after damage to other neurons.

Front 45

What are some problems that limit axon regeneration?

Back 45

1) A cut in the nervous system causes a scar to form, creating a mechanical barrier. Scar tissue is beneficial immediately after the damage, but blocks regrowth of axons later.

2) Neurons on the two sides of the cut pull apart.

3) The glia cells that react to CNS damage release chemicals that inhibit axon growth.

Front 46

What are collateral sprouts?

Back 46

New branches that take over vacant synapses. They are formed by other axons when a cell secretes neurotrophins after losing input from a particular axon.

Front 47

Is collateral sprouting helpful or harmful?

Back 47

Depends on whether the sprouting axons convey information similar to those that they replace.

Front 48

What is denervation supersensitivity?

Back 48

Helps compensate for decreased input by enhancing responses to other synapses (more responsive, more easily stimulated).