Neuro Exam Eye

Front 1

What physical property of light is most closely related to the perception of color?

Back 1

Light is electromagnetic radiation, which has three properties: wavelength, frequency, and amplitude. Wavelength is closely related to the perception of color because wavelengths
of 400-700 nm are visible to the naked human eye. Within this visible spectrum, different
wavelengths appear as different colors.

Front 2

Name eight structures in the eye that light passes through before it strikes the
photoreceptors.

Back 2

The eight structures of the eye through which light passes before striking the
photoreceptors are the cornea, the aqueous humor, the lens, the vitreous humor, the ganglion
cell layer, the inner plexiform layer, the inner nuclear layer, and the outer plexiform layer

Front 3

What is myopia, and how is it corrected?

Back 3

Myopia, or nearsightedness, occurs when the eyeball is too long. Parallel rays from a
distant light source, which are bent by the cornea and the lens, normally converge at exactly the same plane as the retina. When the eyeball is too long, the rays of light converge and cross before the retina. As a result, the image on the retina is a blurred circle

This occurs because the amount of refraction that the cornea and the lens provide is too
large to focus distant objects on the retina. To see distant points clearly, nearsighted people
must use artificial concave lenses that help focus the image on the retina.

Front 4

Give three reasons explaining why visual acuity is best when images fall on the
fovea.

Back 4

Visual acuity is best when images fall on the fovea for three reasons: 1) Visual acuity
improves as the ratio of photoreceptors to ganglion cells decreases. Relatively few photoreceptors feed each ganglion cell in the fovea, resulting in a low ratio, which maximizes visual acuity. 2) The fovea sits in a pit that the lateral displacement of the ganglion and bipolar cells creates above the photoreceptors. This allows light to strike the photoreceptors without passing through the other layers of retinal cells, minimizing light scatter that can blur the image. 3) Visual space is not mapped to the targets of visual input uniformly. The central few degrees of the retina are over-represented in “neural space.” Signals from individual cones in the fovea are represented in a larger volume of brain tissue than input from photoreceptors in peripheral regions of the retina. This specialization contributes to high acuity in central vision.

Front 5

How does the membrane potential change in response to a spot of light in the receptive field center of a photoreceptor? Of an ON bipolar cell? Of an OFF-center ganglion cell? Why?

Back 5

Photoreceptors hyperpolarize in response to light. As a result, they release less neurotransmitters at the photoreceptor/bipolar cell synapse. ON-center bipolar cells depolarize in response to light in the receptive field center. This is their response to lessglutamate release at the photoreceptor/bipolar cell synapse. ON-center ganglion cells depolarize in response to light in the receptive field center. These ganglion cells receive direct input from ON-center bipolar cells.

Front 6

What happens in the retina when you “get used to the dark”? Why can’t you see color at night?

Back 6

Getting used to the dark is called dark adaptation. This capability is a consequence of a duplex retina, in which cones function best at high levels of illumination and rods function best at low levels of illumination. When moving from high to low levels of illumination, the retina must be adapted to the dark before the rods are maximally sensitive. Dark adaptation is a biochemical process in which rhodopsin, the rod photopigment, regenerates after being bleached in the light. The functional circuitry of the retina also readjusts as rhodopsin regenerates. Consequently, information from more rods is available to ganglion cells. The regeneration of unbleached rhodopsin and the resulting changes in functional circuitry take about 20-25 minutes. At night, it is difficult to detect colors because the cones, which have three photopigments with different spectral sensitivities, are inactive. Only cones are capable of color vision. At low levels of illumination, only rods are active and they contain only one photopigment. Rhodopsin’s peak sensitivity is 500 nm.

Front 7

In retinitis pigmentosa, early symptoms include the loss of peripheral vision and
night vision. The loss of what type of cells could lead to such symptoms?

Back 7

Rods are responsible for night vision. The degeneration of rod photoreceptors can lead
to early symptoms, such as loss of peripheral and night vision. The density of rod photoreceptors increases in the peripheral retina.

Front 8

Rods are much more sensitive to light than cones
because

Back 8

B. Rods have much higher concentration of
photopigment.

Front 9

The molecule in the rod that is directly affected by
photons is called

Back 9

Rhodopsin.

Front 10

All humans have a blind spot in their eye because of the
presence of the

Back 10

Optic disk

Front 11

What is the flow of information in the retina?

Back 11

Photoreceptor, bipolar cell, ganglion cell.

Front 12

What is the difference between ON-center ganglion cells and OFF-center
ganglion cells?

Back 12

ON-center ganglion cells receive input from ON
bipolar cells while OFF-center ganglion cells receive input
from OFF bipolar cells.

Front 13

The ability of the eye to distinguish two points that
appear close together is called

Back 13

Visual acuity.

Front 14

How is the aqueous humor different from the vitreous humor?

Back 14

Aqueous humor lies behind the cornea while the
vitreous humor lies between the lens and the retina.

Front 15

What is the total number of different photopigment types
that are contained in the rods and cones of the retina?

Back 15

4

Front 16

How is phototransduction in cones different from that in
rods?

Back 16

Cones have different opsins.

Front 17

Pupils change size in response to different lighting
conditions. This is called:

Back 17

Pupillary light reflex.

Front 18

On a moonless night, one can see a dim star best with
one's

Back 18

Peripheral retina

Front 19

Most of the light refraction in our eye is done by the

Back 19

Cornea

Front 20

The only cell that has a axon that leaves the retina is the

Back 20

Ganglion cell

Front 21

Which cells actually capture the light energy within the
eye?

Back 21

Photoreceptors.

Front 22

A single photon can be detected by the eye because one
molecule of rhodopsin can activate many molecules of
phosphodiesterase, a process called

Back 22

Amplification.

Front 23

How do we focus on objects located at a distance less than 9 m from the eye

Back 23

A change in the shape of the lens

Front 24

What is absorption?

Back 24

The transfer of light energy to a particle or
surface

Front 25

The structure of the eye responsible for converting light
energy into neural activity is

Back 25

Retina.

Front 26

Which of the following corresponds to the photoreceptor “dark current

Back 26

At rest, the membrane potential of a rod outer
segment is about –30 mV.

Front 27

Which of the following is a role proposed for movement sensitive
neurons in the parietal area called MST?

Back 27

Navigation

Front 28

Mr. Stewart underwent a surgery to remove a tumor in his brain. During
the surgery, lesions developed in the optic radiations. What is the
potential impact of these lesions

Back 28

Blindness

Front 29

The fact that only spiny stellate cells are found in layer IVC suggests that
layer IVC is involved in what type of projections?

Back 29

Projecting to neighbouring layers of the cortex

Front 30

What is the purpose of the decussation at the optic chiasm?

Back 30

To have each visual hemifield processed by the
contralateral side of the brain

Front 31

Beyond the optic chiasm (i.e. after axonal decussation), a lesion in any
tract (i.e., optic
tract or optic radiation) will cause which of the following symptoms?

Back 31

Loss of the contralateral visual hemifield

Front 32

Which of the following is the function of direction-selective striate cortex neurons

Back 32

Analysis of object motion

Front 33

Layers V and VI are involved in long-range projections from cortex.
Which type of
neuron would most likely be involved in such connections

Back 33

Pyramidal cells.

Front 34

Which of the following is a region of sensory surface that, when
stimulated, changes the membrane potential of a neuron?

Back 34

Receptive Field

Front 35

Which of the following is the common characteristic in the receptive
fields in the ganglion cells of the retina, the LGN, and striate cortex
neurons in layer IVC?

Back 35

Center surround antagonism

Front 36

The MAJOR target of the optic tract in the human is the

Back 36

Lateral geniculate nucleus of the thalamus

Front 37

At the optic chiasm, some fibers from the retina cross from one side of
the brain to the
other, a process called

Back 37

Decussation

Front 38

The projection from the LGN to cortex is called the

Back 38

Optic radiation

Front 39

What is the most likely deficit resulting
from a V4 lesion?

Back 39

Color perception

Front 40

Susan fell down the staircase and injured her head, causing a transection
of the left optic nerve. What is the consequence of this lesion?

Back 40

Blindness in the left eye

Front 41

Where are the first binocular neurons encountered in the retinofugal
projections?

Back 41

LGN

Front 42

Visual cortex is divided into ________ layers

Back 42

6

Front 43

Which ganglion cell axons cross to the opposite side of the brain at the
optic chiasm?

Back 43

Axons from the nasal retina

Front 44

Which of the following is the major source of synaptic input to the LGN?

Back 44

Striate cortex

Front 45

What is the correct order of the structures through which visual
information passes from the retina to cortex

Back 45

optic nerve, optic chiasm, optic tract

Front 46

What is the biggest clue that information from different retinal ganglion
cell types are
kept separate in the LGN?

Back 46

The fact that M-cells project only to layers 1 and
2 of the LGN

Front 47

The majority of ganglion cells are _______, which have _______ receptive
fields

Back 47

P cells, small

Front 48

"Ganglion cells that are neighbours in the retina have axon terminals that
are
neighbours in central visual structures." This organisation is an example of

Back 48

Retinotopic mapping

Front 49

. After 10
million years of living under these conditions, you would expect the
population of this lost people to contain a high percentage of ______ in
their retinas, compared with people living on the surface of the earth.

Back 49

Rod photoreceptors.

Front 50

Which of the following is NOT a target of the optic tract

Back 50

Visual cortex

Front 51

Changes in hair cell receptor potential results from the
opening of potassium channnels on the tips of the
stereocilia when the cilia bend. These receptors are a
type of

Back 51

mechanoreceptor.

Front 52

The base of the basilar membrane can be described as

Back 52

Stiff, narrow, and especially sensitive to high
frequencies.

Front 53

Which of the following triggers movement of the ossicles in the auditory
pathway?

Back 53

Tympanic membrane

Front 54

Which of the following contributes to the pressure at the oval window
being 20 times greater than that at the tympanic membrane?

Back 54

Ossicles act like levers

Front 55

The main difference between the response of hair cells in
the auditory system and other neurons when K+ channels open is

Back 55

the opening of K+ channels depolarize the hair cells
but hyperpolarize most neurons.

Front 56

The initial stages of the basic auditory pathway is

Back 56

Sound wave moves the tympanic membrane
Tympanic membrane moves the ossicles
Motion at the oval window moves the fluid in the
cochlea
Movement of the fluid in the cochlea causes a response
in sensory neurons

Front 57

Why is movement at the oval window accompanied by a complementary motion at the round window

Back 57

Incompressible fluid in cochlea

Front 58

How do the pinnae of humans differ from the pinnae of
other animls such as cats and horses?

Back 58

humans cant move pinna

Front 59

Which of the following contains auditory receptor neurons?

Back 59

Organ of Corti

Front 60

The number of compressions or rarefactions of a sound
wave that passes by our ears each second is known as___ of sound and is expressed in units called

Back 60

Frequency, hertz

Front 61

All ascending auditory pathways converge on the

Back 61

Inferior colliculus.

Front 62

Identify the two structures that are separated by the tympanic
membrane.

Back 62

The auditory canal and the middle ear

Front 63

Compared with other extracellular fluids, endolymph has
an unusually

Back 63

High K+ concentration

Front 64

The fluid in the inner ear has greater inertia than in the
outer ear, and more pressure is needed to vibrate the
fluid that the air can provide. This amplification in
pressure is known as ______________ which is the function of the ___ ear

Back 64

sound force amplification, middle

Front 65

Output of the nuclei in the brain stem that process neural
responses to sound generated by the inner ear is relayed
to the __________ in the thalamus.

Back 65

medial geniculate nucleus.

Front 66

Deafness in only one ear can occur from unilateral damage to the

Back 66

Cochlea nuclei

Front 67

Phase locking can be used to code for _____ frequencies, tonotopy can
be used to code for _________ frequencies and both phase locking and
tonotopy are useful for coding ___________ frequencies.

Back 67

Low, High, Intermediate

Front 68

Following the principle of delay lines, a sound coming from one side will
cause optimal summation in the superior olive via afferents from

Back 68

the longest axon from the ipsilateral cochlear nucleus,
and shortest axon from the contralateral cochlear nucleus

Front 69

Unilateral cortical lesion of striate cortex leads to complete blindness in
one visual hemifield, whilst auditory function is still retained to a certain
extent after unilateral lesions because

Back 69

Each eye sends output of the hemifield to only the
contralateral hemisphere while each ear sends output to
both hemispheres

Front 70

A neuron in the auditory system is the most responsive to sound at one
frequency. This is known as

Back 70

Characteristic frequency.

Front 71

The columnar organization present in A1 is on the basis of:

Back 71

Frequency

Front 72

A neuron in the auditory system is the most responsive to sound at one
frequency. This is known as

Back 72

Characteristic frequency.

Front 73

What is one explanation for why there are so many central auditory relay
nuclei?

Back 73

It takes a lot of neural tissues to ascertain

Front 74

The duplex theory refers to the use of:

Back 74

Differences in time, phase and intensity for
horizontal localization

Front 75

Nearby neurons have similar characteristic frequencies and the
systematic organisation of characteristic frequency within an auditory
structure is called

Back 75

Tonotopy.

Front 76

Which structure is the first in the auditory pathway to have binaural
neurons?

Back 76

Superior olive.

Front 77

Medial geniculate neurons have axons that terminate predominately in
which layer of the primary auditory cortex?

Back 77

Layer IV.

Front 78

Where do the cell bodies (somas) of the primary afferent
axons of the somatic sensory system lie?

Back 78

Dorsal root ganglion.

Front 79

What type of information does the dorsal column-medial lemniscal
pathway carry?

Back 79

Touch and proprioception

Front 80

Lesion in which part of the brain would cause a neglect
syndrome, where a part of the body or a part of the world
is ignored or suppressed?

Back 80

Parietal.

Front 81

What kind of receptive field property would give the
highest resolution in a sensory system?

Back 81

Small receptive field

Front 82

Touch and proprioceptive information ascends to the
cerebral cortex through which thalamic nuclei?

Back 82

Ventral posterior nuclei

Front 83

Primary sensory afferent axons have widely varying diameters and their
size correlates with the type of receptor to which they are attached.
Which of these axons are the smallest and the slowest

Back 83

Temperature, pain, and itch

Front 84

At what point do the axons of the dorsal column-medial lemniscal
pathway cross to the opposite side of the CNS?

Back 84

The axons from the cells of the dorsal column
nuclei decussate in the medulla.

Front 85

Which of the following is NOT TRUE acout the
topographic map of the body's surface sensations on the
structure in the brain?

Back 85

This topographic map has to be continuous.

Front 86

What are mechanoreceptors?

Back 86

Sensitive to physical distortion

Front 87

A dermatome is the

Back 87

Area of skin innervated by the dorsal roots of a
single spinal segment.

Front 88

Which quality of the somatic sensory cortical organization does the
distortion of the sensory homunculus reflect?

Back 88

The relative size of the cortex that is devoted to each
body part is correlated with the density of the sensory input
received from that part.

Front 89

A disease that usually affects only one dermatome is

Back 89

Shingles

Front 90

Pressure in the heart and blood vessels and stretching of
the digestive organs are perceived by

Back 90

Mechnoreceptors.

Front 91

To which stimuli do the majority of nociceptors respond

Back 91

Mechanical, Thermal, Chemical

Front 92

Nociceptors are found in most body tissues except

Back 92

Brain

Front 93

Small injections of morphine or endorphins into the dorsal horn can
produce

Back 93

Analgesia

Front 94

Jack felt some initial pain after being stabbed in the arm, but soon felt
no pain at all. Which neural region was probably engaged in increased
activity during this time

Back 94

The periaqueductal gray matter.

Front 95

As it relates to the gate theory of pain, mechanoreceptor activation
results in

Back 95

Indirect inhibition of neurons projecting to the
spinothalamic tract

Front 96

Which of the following phenomena would lead to referred pain?

Back 96

Nociceptors from the appendix and the navel synapse
on the same cell in the substantia gelatinosa

Front 97

In large amounts, capsaicin causes analgesia by:

Back 97

desensitizing pain fibers and depleting substance p

Front 98

A patient presents with a deficit in the sensation of pain and temperature
on the left side of his body, but no other sensory deficits. Which region
of the white matter in the spinal cord has most likely been damaged

Back 98

Ventral spinal cord on the right side

Front 99

The dorsal column-medial lemniscal pathway and the spinothalamic
pathway are significantly different. In what ways are the two pathways
similar?

Back 99

Both pathways synapse in the VP nucleus of the
thalamus

Front 100

At what point do the axons of the spinothalamic pathway cross to the
opposite side of the CNS?

Back 100

Axons of the spinothalamic pathway cross
immediately in the spinal cord and ascend contralaterally.

Front 101

Aspirin is often administered to alleviate pain. From what you know
about nociceptors, how might aspirin work?

Back 101

By inhibiting the synthesis of prostaglandins