Flashcards in mini exam 2 chap 5 Deck (52):
The human central nervous system:
begins to form when the embryo is about two weeks old
The ability of the brain to change its anatomy over time, within limits, is known as:
The fluid-filled cavity of the developing neural tube becomes the: (see p. 124 and review p. 95)
What is the production of new neurons called?
After cells have differentiated as neurons or glia, they:
Chemicals known as ____ and ____ guide neuron migration.
What is the process called when a primitive neuron begins to develop dendrites and an axon?
Which of the following would most likely interfere with migration of neurons during development?
altering the chemical paths
For some axons, glial cells produce an insulating sheath that makes rapid transmission possible. What is this process called?
The stages of neurogenesis that occur for the longest duration are:
myelination and synaptogenesis
New neurons have been found to grow in all of the following cases, except:
spinal cord of mammals.
Brain cells that are neither neurons nor glia, but which are capable of dividing and then differentiating into neurons or glia are called:
What happened when Weiss grafted an extra leg onto a salamander adjacent to one of the hindlegs?
Branches of axons from the old leg attached to corresponding muscles in the new.
When Robert Sperry cut a newt's optic nerve and rotated the eye by 180 degrees, each axon:
regenerated to the area where it had originally been.
Competition of neurons for postsynaptic sites results in survival of only the most successful axons. This general principle is called:
Why is it that all neurons in a healthy adult brain have made appropriate connections?
If an axon does not make the appropriate connections by a certain age, it dies.
What is signaled by nerve growth factor (NGF)?
that a target cell has "accepted" an axon
is cell death caused by an injury or a toxic substance
is a programmed mechanism of cell death.
The function of neurotrophins is to:
promote survival of axons.
In development, neurotrophins ____. During adulthood, they ____.
preserve neurons, increase neuronal branching
The most likely explanation for the excess proliferation of neurons in early development is that it:
compensates for connection errors.
Compared to an adult, a fetus has:
An iodine deficiency in the diet can lead to an inadequate production of thyroid hormones. What is the result if this occurs in an infant or developing fetus?
The most likely reason that children with Fetal Alcohol Syndrome have brain abnormalities is because alcohol:
. decreases release of neurotrophins.
Children of mothers who smoke cigarettes during pregnancy are at an increased risk of:
Varied environment with stimulation increases animals:
branching of dendrites.
The areas of the cortex used by expert video game players are most likely to ____ than the same cortical areas of those who don't play video games.
What is different about rats raised in an enriched environment in comparison to rats raised in an impoverished environment?
improved learning performance
Which of the following factors seems to be particularly important for branching of neurons during brain development?
Closed head injury is
the most common cause of brain damage in young adults.
Which of the following is the most common cause of a stroke
ischemia from an obstruction of an artery
A stroke which is caused when an artery ruptures is also known as:
After ischemia, penumbra cells:
lose much of their oxygen and glucose supplies.
____ cells proliferate after a stroke.
A stroke kills neurons in two waves, first by ______ and second by _______.
Although the following methods may or may not actually work, which method would theoretically be of potential benefit to stroke victims?
blocking glutamate receptors
Tissue Plasminogen activator (tPA):
is helpful in cases of ischemia.
Penumbra, as related to stroke, refers to the:
brain region that surrounds the immediate damage.
To date, the most effective laboratory method minimizing the damage resulting from stroke in nonhuman animals has been to:
cool the brain.
A lesion in the hypothalamus can lead to decreased activity in the cerebral cortex, even though the cerebral cortex is undamaged. The decreased activity in the cortex because of the loss of incoming neurons is called:
Which of the following treatments would be most likely to help a patient starting several days after a stroke?
giving stimulant drugs combined with physical therapy
Which axons will regenerate to a significant degree if cut or crushed?
those in the peripheral nervous system but not in the central nervous system
One reason why axons regenerate better in the peripheral nervous system of mammals than in the central nervous system is that the peripheral nervous system:
produces a chemical that promotes axon growth.
After damage to a set of axons, neurotrophins induce nearby: (refer to p.142)
uninjured axons to form new branches.
Supersensitivity results from a(n) ____ in the number of receptors and a(n) ____ in the effectiveness of those receptors.
A cortical cell originally responded to stimulation of the middle finger. After amputation of that finger it begins responding to the second and fourth fingers. What most likely accounts for this?
Investigators recorded activity from the cerebral cortex of monkeys that had an entire limb deafferented twelve years earlier. Much to their surprise, what did they find?
This whole cortical area had become responsive to the face.
The area of the cortex that receives input from the face is adjacent to the area of the cortex that receives input from the foot. After amputation of the foot, it is possible that a phantom limb sensation will be felt whenever the:
face is touched.
Sensations from phantom limbs:
are a result of brain reorganization.
A monkey with one deafferented limb:
does not use it, even though it can still control the muscles.