Deck 9: Experience-Guided Neural Development

Question 1

When wearing prism glasses, the human brain can compensate for reversed vision by

A) chemoaffinity in the retina.
B) changing connections from the eye to the brain.
C) changing neuronal connections in the visual cortex.
D) adaptation of brain regions that interpret vision.

Answer 1

D

Question 2

If visual input is reversed, humans learn to behave normally, but amphibians continue to show misdirected behavior toward visual cues, suggesting that

A) amphibians use higher brain centers to adjust behavior to fit visual input.
B) humans use higher brain centers to adjust behavior to fit visual input.
C) amphibians cannot regenerate optic nerve damage.
D) humans can regenerate optic nerve damage.

Answer 2

B

Question 3

If half of a frog's retina is lesioned when the optic nerve is cut, the projections from the remaining retinal neurons will innervate _______ to produce a(n) _______ projection on the tectum.

A) the entire tectum; expanded
B) only their original part of the tectum; expanded
C) the entire tectum; compressed
D) only their original part of the tectum; compressed

Answer 3

A

Question 4

If half of a frog's tectum is lesioned when the optic nerve is cut, the projections from the remaining retinal neurons will innervate _______ to produce a(n) _______ projection on the tectum.

A) the entire tectum; expanded
B) only their original part of the tectum; expanded
C) the entire tectum; compressed
D) only their original part of the tectum; compressed

Question 5

If an amphibian recovering from a severed optic nerve is kept in the dark, the retinal ganglion cells will

A) not project to the tectum.
B) have less refined connections to the tectum.
C) still project normally to the tectum.
D) project to random spots of the tectum.

Question 6

In the visual system of both prey and predator species,

A) half of the axons in each optic nerve cross the midline.
B) visual input from the left eye projects to the right side of the brain.
C) visual input from the left visual field projects to the right side of the brain.
D) there is very little overlap in the visual fields of the two eyes.

Question 7

When two eyes were made to innervate the same tectum in frogs,

A) the two eyes did not project in a topographic manner.
B) each eye innervated mutually exclusive stripes of tectum.
C) both eyes projected evenly over the entire tectum.
D) two separate visual fields, one from each eye, were projected onto each half of the tectum.

Question 8

The results of the three-eyed frog experiment, in which two eyes were made to innervate the same tectum, suggested that

A) retinal cells compete for space on the tectum.
B) the tectum adjusts its size to match the degree of input from the retina.
C) the strict view of the chemoaffinity hypothesis is accurate.
D) visual experience is not needed to fine-tune retinotectal projections.

Question 9

In frogs, the segregation of ocular input to the tectum is mediated by _______ receptors and occurs _______.

A) AMPA; throughout life
B) AMPA; only in development
C) NMDA; throughout life
D) NMDA; only in development

Question 10

Amblyopia, or "lazy eye," can be caused by

A) a severed retina.
B) an unfocused image on the retina.
C) damage to the cornea.
D) strabismus.

Question 11

If the right eye of a cat is sutured closed for one month starting at birth,

A) vision in the right eye would return when the eye was opened.
B) the cat would never gain vision in the right eye.
C) light will never be able to enter the right eye.
D) the left eye would compensate by developing a wider visual field.

Question 12

Temporary monocular deprivation in the right eye of an 8-month-old cat will result in most visual cortical cells responding

A) to both eyes in adulthood.
B) only to the left eye in adulthood.
C) only to the right eye in adulthood.
D) only to one eye or the other.

Question 13

Temporary monocular deprivation in the right eye of an 8-week-old cat will result in most visual cortical cells responding

A) to both eyes in adulthood.
B) only to the left eye in adulthood.
C) only to the right eye in adulthood.
D) only to one eye or the other.

Question 14

Blocking action potentials with TTX in the retinal ganglion cells of one eye has the same effect as monocular deprivation in development. This suggests that

A) visual cortical cells normally respond to input from only one eye.
B) synapses from the eye to the visual cortex do not behave in a Hebbian manner.
C) ocular dominance patterns do not respond to neural activity in the eyes.
D) ocular dominance patterns are influenced by neural activity in the eyes.

Question 15

Inducing strabismus in the right eye of an 8-week-old cat will result in most visual cortical cells responding

A) to both eyes in adulthood.
B) only to the left eye in adulthood.
C) only to the right eye in adulthood.
D) only to one eye or the other.

Question 16

What is one effect of strabismus on the visual system?

A) Increased number of visual cortical cells with binocular connections
B) Disparate input from the eyes reaching the brain
C) Reduced depth perception
D) Reduced field of view

Question 17

The effect of neuronal activity on ocular dominance patterns in mammals is mediated by _______ receptors.

A) AMPA
B) acetylcholine
C) NMDA
D) GABA

Question 18

Owl tectal neurons respond to auditory cues according to their

A) pitch.
B) location in space.
C) volume.
D) frequency.

Question 19

If owlets are fitted with prisms that shift the visual field by 10°, auditory localization will

A) be processed by neurons separate from visual neurons.
B) not be functional.
C) be shifted by 10° on the tectal map to match the visual shift.
D) be unaffected.

Question 20

Mice can detect more odors than humans because they have

A) more olfactory receptor genes.
B) more functional olfactory receptor proteins.
C) larger olfactory epithelia.
D) olfactory glomeruli that project directly to the cortex.

Question 21

Closing the nostril openings of a newborn mouse results in more olfactory sensory neurons that

A) express more than one olfactory receptor gene.
B) cannot detect odor.
C) express only one olfactory receptor gene.
D) undergo apoptosis.

Question 22

Olfactory sensory neurons with a mutation that prevents them from firing action potentials in response to odorants usually do not survive to project to glomeruli because

A) they cannot follow the ephrin gradient.
B) they cannot follow semaphorins.
C) their neighbors fire competing action potentials.
D) the mutation triggers apoptosis.

Question 23

If a whisker on a newborn mouse is removed, what will happen to the area of the somatosensory cortex that would have received information from that whisker?

A) It will still receive information from the whisker, but will not fire any action potentials.
B) No neurons will project there.
C) It will receive information from the neighboring whiskers.
D) That cortical area will not develop.

Question 24

If a human suffers a hand amputation as an adult, what will happen to the area of the somatosensory cortex that previously received information from the lost hand?

A) The projections from the hand will still be there, but will be inactive.
B) The projections from the hand will die, and that area of the cortex will be empty.
C) Projections from the face and neighboring limb will expand to control that cortical area.
D) That cortical area will die.

Question 25

In rats, monkeys, and humans, tactile experiences shape the brain's somatosensory cortex map

A) only in fetal development.
B) only in early childhood.
C) only during puberty.
D) throughout life.

Question 26

How do adult humans and amphibians respond differently if vision is reversed either by prism glasses or by surgery?

Question 27

Refer to the figure.
In the normal amphibian, the topographical projection from the eye to the tectum is mapped onto the tectum in such a way that the projection of the visual field is rotated 90° (A). If the optic nerve is cut, and the eye rotated 180°, the projection of the visual field is mapped onto the tectum as shown in (B). What does this result suggest about how the optic nerve regenerates its retina-tectum connections? What would this mean for the amphibian's behavior after the optic nerve regenerates?

Question 28

What did the results of the "tectal expansion" and "tectal compression" experiments indicate about the chemoaffinity hypothesis? Why might amphibians require this kind of system for retinotectal innervation?

Question 29

What are three influences on the development of retinotectal projections in amphibians?

Question 30

Many species that are subject to predation have eyes directed to the sides. In what way does this arrangement make the visual field and the optic nerve fiber tract differ between prey species and predator species? How might this specifically benefit prey and predator species?

Question 31

Michael May was blinded at three years of age, and his vision was restored 40 years later. Despite clear images entering his eye after visual restoration, he still had trouble recognizing his wife's face and distinguishing between objects. Which synaptic mechanisms might have been impaired that prevented Michael from regaining full use of his vision? What would have happened to his vision, after restoration, had he been blinded as an adult instead?

Question 32

Refer to the figure.
The ocular dominance histograms shown illustrate the strength of the response of cortical neurons to stimuli presented to either the left or the right eye in cats that developed normally (A), cats with one eye closed during development (B), and cats with both eyes closed during development (C). What happens to cortical neurons when one eye is closed during development? Why does binocular deprivation result in ocular dominance patterns similar to that in a cat with normal vision?

Question 33

In owls, what is the relationship between neurons that respond to visual cues and neurons that respond to auditory cues? How does this arrangement affect owl behavior?

Question 34

How does the olfactory system of adult mice differ from that of newborn mice? What process drives this difference?

Question 35

In general, how does sensory experience guide neural development? What benefit does this have?