Physio Ii Test 3: Neuro Lectures 5-6 : Vision

Front 1

What is the major clue for stereopsis (depth perception)?

Back 1

-retinal disparity

Front 2

ipRGCs

Back 2

-intrinsically photosensitive retinal ganglion cells
-small percentage of ganglion cells
-contain melanopsin a photopigment which allows them to respond directly to light
-less sesnsitive to light than rods and cones bc of low pigment density
-response to light is depolarization
-non-image forming vision and participate in pupillary light reflex and circadian rhythms

Front 3

strabismic amblyopia

Back 3

-reduction or total loss of vision in deviated eye
-find few or no cortical cells driven by deviated eye
-ganglion and geniculate fields appear normal

Front 4

What can rod cells do that cones cannot?

Back 4

-detect dim light

Front 5

strabismic alternator

Back 5

-a few strabsmic children alternate the eye doing the fixating
-monocular visual acuity remains unimpaired but there is a loss of stereopsis (3 dimensional vision)
-experiments with kittens and alternating patches = normal receptor fields arranged in columns but no binocular interaction

Front 6

presbyopia

Back 6

loss of accomodation. results from loss of lens elasticity as a consequence of aging.

"old man's eyes"

Front 7

strabismus after age ____ leads to persistant double vision

Back 7

age 9

Front 8

Axons from optic tract to superior colliculus

Back 8

-participates in reflex orienting the head in response to visual or other stimuli
-these projections might explain phenomenon of "blind sight"

Front 9

the image on the retina is

Back 9

inverted and switched left to right

Front 10

axons from optic tract to hypothalamus

Back 10

-projections to suprachiasmatic nucleus of hypothalamus
-probably act to train biological clock

Front 11

Emmetropia

Back 11

with normal eyes at rest, parallel light rays are exactly focused on retina (fovea)

Front 12

axons from optic tract to pretectal area

Back 12

-at junction of midbrain and diencephalon
-pretectal neurons project to edinger-westphal nucleus
-participate in pupillary light reflex

Front 13

Ametropia

Back 13

An eye abnormality, such as nearsightedness, farsightedness, or astigmatism, resulting from faulty refractive ability of the eye.

Front 14

Where do the frontal eye fields project to?

Back 14

-superior colliculus
-caudate nucleus
-horizontal and vertical gaze centers

Front 15

Myopia

Back 15

near-sighted. point of focus of parallel rays of light is in front of retina

Front 16

Where are the frontal eye fields located?

Back 16

Brodmann's area 8 in frontal lobe

Front 17

Hypermetropia

Back 17

Far-sighted. point of focus of parallel rays of light is behind retina.

Front 18

Where do the frontal eye fields receive input from?

Back 18

-from primary and association areas of visual cortex, supplementary eye feilds, dorsolateral prefrontal cortex, and auditory and somatosensory association areas

Front 19

Astigmatism

Back 19

asymmetry of curvature of cornea or lens, causes difference in refractivity.

Front 20

4 physiological layers of the retina

Back 20

1) Ganglion layer
2) Bipolar Layer
3) Photoreceptor Layer
4) Pigment Epithelium

Front 21

retinal blur

Back 21

target out of focus

Front 22

3 types of neurons in bipolar layer.

Back 22

1) bipolar cells
2) horizontal cells
3) amacrine cells

Front 23

when light hits the retina. What is the order of physiological layers it must travel through?

Back 23

Light
↓
1) Ganglion layer
↓
2) Bipolar Layer
↓
3) Photoreceptor Layer
↓
4) Pigment Epithelium

Front 24

What are the output cells of the retina?

Back 24

The axons of Ganglion cells form the optic nerve

Front 25

what neurons in the bipolar cellar connect photoreceptor to photoreceptor?

Back 25

Horizontal cells

Front 26

What type of photoreceptive cells are found in the foveola

Back 26

only type of photocells = cones

NO RODS

Front 27

What type of photoreceptive cells are found in the optic disk?

Back 27

NO PHOTORECEPTORS IN OPTIC DISK

Blind spot

Front 28

What type of photoreceptive cells are responsible for color

Back 28

Cones are responsible for color

Front 29

What type of photoreceptive cells are responsible daylight (photopic) vision?

Back 29

Cones are responsible for daylight vision

Front 30

Where does the ganglion cell axon leave the eye?

Back 30

optic disk (blind spot)

Front 31

scotopic vision

Back 31

dim light vision (Rods)

Front 32

Photopic vision

Back 32

day light vison (Cones)

Front 33

achromatic vision

Back 33

colorless vision (rods)

Front 34

Which photoreceptive is considered more sensitve?

Back 34

Rods are more sensitive than Cones

Rods: 1 photon produces a response

Cones: 10's-100's photons required for response.

Front 35

Duplicity theory of vision

Back 35

vision is mediated by 2 photoreceptor types:
1) rods for low light
2) cones for bright light

Front 36

Where are photoreceptive cells found?

Back 36

Rentina

Front 37

What cell type in the bipolar layer produces AP?

Back 37

Amacrine cells produce AP

Front 38

What photoreceptive cells is responsible for dim light (scotopic) vision?

Back 38

rod are responsible for scotopic/dim light vision

Front 39

Macula Lutea

Back 39

The fovea is a pit in the middle of the Macula.

The macula is cone rich

Front 40

Where does light have direct access to cones and is considered the region of highest acuity ?

Back 40

foveola only has cones there for increased probability of light reaching one.

Front 41

All visual pigments have a common structure of Chromophore+opsin. What is constant among all visual pigments and what varies

Back 41

The Chromophore 11-cis retinal is always present, but the opsin varies.

Front 42

What is the light absorbing portion of the visual pigment?

Back 42

Chromophore (11 cis retinal) is the light absorbing portion of the visual pigment

Front 43

What imparts spectral sensitivity to the visual pigment?

Back 43

opsin

Front 44

The Rod (achromatic vision) visual pigment Rhodopsin contains 11-cis retinal and what opsin?

Back 44

scotopsin

peak absorption 500nm (blue-green)

Front 45

The Cone (chromatic vision) visual pigments contain 11-cis retinal and 1 or 3 types of opsin. Name them and their wavelength.

Back 45

1) red-sensitive (long wavelength)
2) green-sensitive (medium wavelength)
3) blue-sensitive (short wavelength)

Front 46

Protanopia

Back 46

Color blindness:

loss of red-sensitive (long wavelength)

Front 47

Strabismus may cause irreversible blindness in children, but in adults it only causes ____

Back 47

Strabismus in adults causes diplopia (double vision)

Front 48

diplopia

Back 48

double vision

Front 49

Strabismus amblyopia

Back 49

reduction or total loss of vision in deviated eye

Front 50

What is the major binocular cue?

Back 50

retinal disparity is the major clue for steropsis

Front 51

monocular cues at distances ___ than 100 ft

binocular cues at distances ___ than 100 ft

Back 51

monocular cues at distances greater than 100 ft

binocular cues at distances less than 100 ft

Front 52

what retinal structure contains the foveola?

Back 52

Macula leuta

Front 53

11-cis retinal is a ___

Back 53

11 cis retinal is an chromophore

Front 54

what portion of vestibular pigments is reactive to light?

Back 54

11-cis retinal is an chromophore that is reactive to light

Front 55

What happens to 11-cis retinal when Rhodopsin is hit with light?

Back 55

11-cis retinal --> all-trans retinal
Rhodopsin --> Metarohodopsin II (activated rodopson)

all-trans retinal portion of Metarohodopsin II no longer fits into the opsin binding site. So the now free Metarohodopsin II is free to activate 100 G-protein tranducins.

G-protein tranducens then activates GMP phosphodiesterase which hydrolyses 1000 cGMP/sec.

This greatly decreases of cGMP in the photoreceptor cells and results in the closing of cGMP-dependent Na+ channels.

Closing of cGMP-dependent Na+ channels results in
1) decrease in Dark Current
2) phtoreceptor membrane hyperpolarization (moves toward equilibrium) which decreases Glutamate NT release to bipolar cells

Front 56

does light increase or decrease the amount of glutamate NT releases from photoreceptor cells? Does this result in an increase or decrease to ganglion cells?

Back 56

light hyperpolarizes photoreceptor cells and decreases glutamate NT released to bipolar cells.

This depends on the type of bipolar cell releasing glutamate to ganglion cell:

Off center (Hyperpolarized in dark): - Hyperpolarizes in light,
- ↓GLU released
- ↓AP frequency in ganglion cell.

On center (Depolarized in dark):
- Depolarizes in light
- ↑GLU released
- ↑AP frequency in ganglion cell

Front 57

Is the response to light from photoreceptors graded?

Back 57

Yes, by ↑ or ↓ GLU NT

Front 58

On center bipolar cells reaction to light

Back 58

On center (Depolarized in dark):
- Depolarizes in light
- ↑GLU released
- ↑AP frequency in ganglion cell

Front 59

Off center bipolar cells reaction to light

Back 59

Off center (Hyperpolarized in dark):
- Hyperpolarizes in light,
- ↓GLU released
- ↓AP frequency in ganglion cell.

Front 60

What is the reaction of ganglion cells to Off center bipolar cells?

Back 60

light will cause ↓GLU release from Off center bipolar cells. This will result in ↓AP frequency in ganglion cell.

Front 61

What is the reaction of ganglion cells to On center bipolar cells?

Back 61

light will cause ↑GLU released from On center bipolar cells. This will result in ↑AP frequency in ganglion cell.

Front 62

What is convergence?

Back 62

125 million rods and 5 million cones but only 1.6 million ganglion cells.

Front 63

In relation to the center receptive field, the surround receptive field is always

Back 63

In relation to the center receptive field, the surround receptive field is always OPPOSITE.

on center with off surround
off center with on surround

Front 64

What do horizontal cells do?

Back 64

horizontal cells connect photoreceptors in the surround to photoreceptors in the center.

horizontal cells depolarize photoreceptors in the center (opposite of light)

Front 65

M cells

Back 65

Tells the brain where the object is and if it is moving.

-ganglion cell type
-large receptive field
-No color
-sensitive to movement and small differences in contrast
- found in the 2 ventral layers (magnocellular division) of LGN: layers 1&2

Front 66

Where are M-cells found in the lateral geniculate nuclei (LGN)?

Back 66

M-cells are found in the 2 ventral layers (magnocellular division) of LGN: layers 1&2 (of 6 layers)

Front 67

P-cells

Back 67

What is the object and what color is it?
-small receptive fields
-high spatial resolution encodes fine details
-sensitive to COLOR
-project to 4 dorsal layers (parvocellular areas) of LGN 3-

Front 68

Where are P-cells found in the lateral geniculate nuclei (LGN)?

Back 68

project to 4 dorsal layers (parvocellular areas) of LGN.
layers 4-6 (of 6 layers)

Front 69

ipRGCs

Back 69

intrinsically photosenitive Retinal Ganglion cells (ipRGCs)

participate in non-image forming vision
ex. pupillary light reflex and circadian photo entrainment

Front 70

How do ganglion cells react to light?

Back 70

ipRGCs have a photopigment called melanopsin and DEPOLARIZE when exposed to light

participate in non-image forming vision

Front 71

What is the difference of ipRGCs and photoreceptors in their response to light?

Back 71

ipRGCs: depolarize to light

photoreceptors: hyperpolarize to light

Front 72

↓GLU to ON Center bipolar cells

Back 72

↓GLU from Photrecptor
On centers will depolarize
↑GLU release to ganglion cells
↑ganglion cell AP

Front 73

↓GLU to OFF Center bipolar cells

Back 73

↓GLU from Photoreceptor
Off centers will hyperpolarize
↓GLU release to ganglion cells
↓ganglion cell AP
↓GLU to ON Center bipolar cells

Front 74

Where do 90% of axons from the optic tract go?
The other 10%?

Back 74

90% LGN
10% superior colliculus, hypothalamus, pretectal area

Front 75

What is the function of axons that go to superior colliculus?

Back 75

participate in reflex orienting of head in resposne to other stimuli

Front 76

What is the function of axons that go to hypothalamus?

Back 76

biological clocks to 24hrs

Front 77

What is the function of axons that go to pretectal area?

Back 77

pulillary light reflex

Front 78

Each lateral geniculate nucleus (LGN) receives inputs from ____

Back 78

Each lateral geniculate nucleus (LGN) receives inputs from both eyes.

Front 79

Each geniculate cell receives inputs from ____.

Back 79

Each geniculate cell receives inputs from one eye only

Front 80

T/F Each geniculate cell receives inputs from both eyes?

Back 80

False

Each geniculate cell receives inputs from one eye only

Front 81

The Right LGN receives inputs from both eyes and ___ visual field

Back 81

The Right LGN receives inputs from both eyes and LEFT visual field

Front 82

The left LGN receives inputs from both eyes and ___ visual field

Back 82

The left LGN receives inputs from both eyes and Right visual field

Front 83

is there binocular interaction in geniculate cells?

Back 83

NO, there is no binocular interaction at the lateral geniculate level.

Geniculate cells only receive input from only one eye. The inputs are segmented

Front 84

What are the mangocellular layers of the LGN.

Back 84

large m-cells project to the mangocellular layers of the LGN

layers 1&2

m cells -->mangocellular cells

geniculate cells of layers 1&2 respond like m gangilion cells: color blind, movement sensitive with large receptive field

Front 85

What are the parvocellular layers of the LGN.

Back 85

small p-cells project to the parvocellular layers of the LGN
layers 3-6

p cells -->parvocellular cells

geniculate cells of layers 3-6 respond like p gangilion cells: color with small receptive field

Front 86

See I, I see, I see

What does this tell you?

Back 86

See I, I see, I see
C I I C I C
1,2 3,4 5,6
contra lateral eye: 1,4, 6
ipsilateral eye: 2,3,5

Front 87

layers 2,3,5 of the LGN receive input from what eye

Back 87

See I, I see, I see
C I I C I C
1,2 3,4 5,6
ipsilateral eye: 2,3,5

Front 88

layers 1,4,6 of the LGN receive input from what eye

Back 88

See I, I see, I see
C I I C I C
1,2 3,4 5,6

contra lateral eye: 1,4, 6

Front 89

Geniculate cells project to layer ___ of the primary visual cortex

Back 89

Geniculate cells project to layer 4 of the primary visual cortex

Front 90

is layer 4 of primary visual cortex monocular or binocular?

Back 90

layer 4 of primary visual cortex monocular

Front 91

simple cells receive input from geniculate cells and respond best to

Back 91

simple cells receive input from geniculate cells and respond best to bars of light with correct orientation

Front 92

Where does the majority of focusing occur?

what happens at the lens-vitreous humor interface?

Back 92

Most of the focusing of the image is done at the air-cornea interface.

lens-vitreous humor index can change shape and refractive index. small adjustments to focus are done here.

Front 93

cones out perform rods in all visual tasks except ___

Back 93

the detection of dim light

Front 94

scotopic vison

Back 94

dim light vision

Front 95

photopic vision

Back 95

daylight vison

Front 96

Which of the following cell types produce an action potential?
1)bipolar cells
2)horizontal cells
3)amacrine cells
4)ganglion cells

Back 96

amicrine and ganglion cells produce action potentials

Front 97

what inparts spectral sensitivity to visual pigments

Back 97

opsin, all have 11-cis retinal

Front 98

Metarhodopsin II activates a G-protein called __

Back 98

transducen

Front 99

transducen activates a phosphodiesterase. what role does this enzyme play?

Back 99

phosphodiesterase that hydrolyses cGMP -->5-GMP.
The dark current cGMP dependent Na+ channels will close in response to the decrease of local cGMP. The net effect results in a hyperpolarization of the rod membrane and bring the membrane potential
ENa+ -->EK+ (becomes less negative).

Front 100

What do horizontal cells do to photoreceptors in the surround?

Back 100

horizontal cells depolarize photoreceptors in the center (opposite effect of that of light). The center behaves like it is in the dark when the surround is stimulated by light.

Front 101

What are the 2 main types of ganglion cells?

Back 101

M-cells and P cellls

Front 102

what ganglion cells respond directly to light by depolarization

Back 102

IPRGT

Front 103

ipRGCs participate in non-image forming vison and participate in what 2 processes?

Back 103

1)pupillary light reflex
2)circadian photo entrainment

Front 104

What visual field does the Left LGN look at?

Back 104

The left LGN looks at the right visual field.

Right visual field
Left 1/2 of eyes
Left LGN

Front 105

T/F each geniculate cell receives input from both eyes

Back 105

F,
although one lateral geniculate nucleus carries complete information about the contralateral visual field, the inputs from each eye remain segregated.

Front 106

The Pretectum of the Midbrain Controls___

Back 106

The Pretectum of the Midbrain Controls Pupillary Reflexes

Front 107

The primary visual cortex sees a series of lines, squares,corners, angles. What cortical area makes sense of these shapes and puts them together into something recognizable?

Back 107

association cortex

Front 108

retinal disparity

Back 108

-target not on fovea of both eyes
-binocular clue (within 100ft)
-retinal disparity is the major clue for steriopsis