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Neuro I > Special Senses - Vision > Flashcards

Special Senses - Vision Flashcards

1
Q

If an object is far away, light rays have_____ and _____ rays enter the eye. Does or does not need a lot of refraction.

A

diverged
only parallel
does not need a lot of refraction

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2
Q

If an object is near, light rays are_____. Need ________refaction to make the rays focus on the retina.

A

still diverging

more refraction

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3
Q

To focus an image on the retina, the eye uses

A

refraction

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4
Q

two sights of refraction

A

cornea and lens

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5
Q

cornea role in refraction

A

1st site of refraction
bends light the most of any structure (2/3 of the bending)
the amount of bending is fixed - we can’t control it

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6
Q

why do we need the variable refection provided by the lens

A

so we can see near things and farthings

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7
Q

Accommodation requires what 3 components

A

ciliary muscle, suspensory ligaments, the lens itself

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8
Q

Near vision requires ______ of the ciliary muscle

A

contraction.

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9
Q

when ciliary muscle contracts, the tension on suspensory ligaments ______ . The lens becomes _____

A

is released.

rounder

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10
Q

increasing the curvature of the lens ______ the refractive power of the lens

A

increases. allows the light rays from a nearby object to be bent sufficiently to bring them into focus on the retina

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11
Q

In young children, the lens can add ____ diopters, in the mid 20s, a loss of _____ results in a strength of ___ diopters. By 50s, the lens may be able to add only ____ diopters

A

20
elasticity
10
1

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12
Q

Far vision requires ______ of the ciliary muscle

A

relaxation

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13
Q

when the ciliary muscle relaxes, the tension on suspensory ligaments ______. The lens becomes _______.

A

increases

flat

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14
Q

decreased curvature of the lens _____ refractive power of the lens

A

decreases. if the object is far away, less bending of the parallel light rays is required, the lens needs to be flatter.

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15
Q

The near response includes (3)

A

contraction of ciliary muscles
convergence of eyes to point of focus
constriction of pupil

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16
Q

constriction of the pupil in the near response does what

A

reduces the opening for light to enter, eliminating some diverging light rays - this allows us to focus better.

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17
Q

In the retina, light moves from ____ to _____

A

the inner limiting membrane to the pigment epithelium through multiple layers of cells

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18
Q

in the retina there are multiple cell types (5)

A 
photoreceptor cells
bipolar cells
ganglion cells
horizontal cells
amacrine cells
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19
Q

Light passes through all of the layers of cells (except RPE). as a result, there is

A

distortion of the image that the retina will take care of

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20
Q

Vertical pathway of the retina is composed of (3)

A

photoreceptor
bipolar cell
ganglion cell

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21
Q

The vertical pathway is the pathway for

A

relaying visual information to the brain

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22
Q

The circuit for the _____ seems to be the base for all vision

A

cones

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23
Q

photoreceptors have a constant release of ____

A

glutamate

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24
Q

in the dark - photoreceptor release of glutamate is _____

A

high

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25
Q

when a photon activates photoreceptor, release of glutamate is______

A

low (remember that light hyper polarizes the rods and cones)

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26
Q

Vertical pathway for cones

A
  1. light hits a photoreceptor

2. photoreceptor is hyperpolarized => decreased release of NT (glutamate) onto a bipolar cell

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27
Q

On-center bipolar cell

A

activation of photoreceptor (decrease glutamate to center of cell) in CENTER of bipolar cell’s receptive field causes DEPOLARIZATION of the bipolar cell.

activation of photoreceptor (decreased glutamate to periphery) in the SURROUNDING region causes HYPERPOLARIZATION of the bipolar cell

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28
Q

Off- center bipolar cell

A

activation of photoreceptor (decreased glutamate to periphery) in the SURROUNDING region causes DEPOLARIZATION of the bipolar cell

activation of photoreceptor (decreased glutamate to center of cell) in CENTER of bipolar cell;s receptive field causes HYPERPOLARIZATION of the bipolar cell

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29
Q

When a photoreceptor is activated, where does depolarization occur in an on center bipolar cell as compared to an off center bipolar cell>

A

the center

the periphery

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30
Q

if a photoreceptor activates an on center bipolar cell, what type of receptor are we thinking

A

metabotropic

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31
Q

if a photoreceptor activates an off center bipolar cell, what type of receptor are we thinning

A

AMPA

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32
Q

On-center bipolar cell mechanism

A

metabotropic receptor
NT binding the receptor (DARK) causes a DECREASE in cation influx

so… in the dark, the on-center cell is hyper polarized

with light, photoreceptor releases LESS glutamate, so cation current increases and the on center cell is depolarized

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33
Q

Off-center bipolar cell mechanism

A

AMPA receptor
NT binding the receptor (DARK) causes an INCREASE in cation influx

so… in the dark, the off-center cell is depolarized

with light, photoreceptor releases LESS glutamate, so cation current decreases and the off center cell is hyper polarized

34
Q

Ganglion cells are also On-center and off-center based on

A

whatever their connection bipolar cell is

35
Q

When bipolar cells are depolarized, they release what NT

A

glutamate

36
Q

bipolar cells, when depolarized, release glutamate onto what cells

A

ganglion cells.

37
Q

Ganglion cell axons become

A

the fibers of the optic nerve

38
Q

The first place in the eye we see true action potentials is

A

the ganglion cells.

39
Q

Ganglion cells rely on _____ as NT

A

glutamate

40
Q

Describe the vertical pathway for rods

A

many rods converge on one ON-center bipolar cell
bipolar cell synapses on an A11 amacrine cell
A11 amacrine cell synapses on a cone ON-center bipolar cell
the cone on-center bipolar cell activates a ganglion cell

41
Q

Rods do vision in ______ situations

A

low light

42
Q

need many rods to converge on a _______. WHy>

A

bipolar cell. to increase our chances of seeing what we need to see.

43
Q

Role of on and off center cells

A

these two types of cells help us increase the ability to detect edges and sharpen our vision

44
Q

on center cells tell us

A

where something is

45
Q

off center cells tell us

A

where something ends.

46
Q

amacrine cells and horizontal cells

A

provide inhibitory signals that modify the activity of neighboring photoreceptors, bipolar cells or ganglion cells

47
Q

Action potentials occur in what cells

A

ganglion cells

48
Q

axons from ganglion cells will become

A

fibers of the optic nerves

49
Q

the retina from each eye sees ______ visual fields

A

two different

50
Q

The Left temporal retina is activated by light coming from

A

the right visual field

51
Q

the right nasal retina is activated by light coming from

A

the right visual field

52
Q

the right temporal retina is activated by light coming from

A

the left visual field

53
Q

the left nasal retina is activated by light coming from

A

the left visual field

54
Q

at the _____ the axons from the ______ retina on each side will cross and join the axons from the _____retina

A

optic chiasm
nasal retina
temporal retina

55
Q

Crossing at the optic chiasm allows what

A

all of the information from one visual field to be sent to the same part of the brain (the side opposite the visual field)

56
Q

after the axons cross at the optic chiasm, they synapse where

A

lateral geniculate body

57
Q

cells in the LGN are of what type

A

on and off center as well

58
Q

functions of the LGN (4)

A
  1. control motions of the eyes - so they converge on the desired point of interest
  2. control focusing - so that the image we are interested in is in the best focus possible
  3. identify major elements within our visual image - send that info to the cortex
  4. identify motion
59
Q

The neocortex is divided into ____ layers of cells

A

6

60
Q

Primary visual cortex =

A

V1

61
Q

layers 1, 2, 3 allow

A

networking between V1 and other parts of the cortex

62
Q

layer 4

A

receives inputs from the LGN

63
Q

Layers 5 and 6

A

send information back to the LGN

64
Q

cortex is divided from a functional standpoint into

A

columns

65
Q

each column does _____

neighboring columns have _____

A

a different job

related jobs

66
Q

There are a lot of columns in V1 that receive input from photoreceptors in the macula

A

in part bc that is the place where receptor density is the greatest

67
Q

peripheral regions of the retina have much less area in V1 devoted to them

A

few receptors, many of which converge onto the same bipolar cells

68
Q

MAJOR JOB OF V1

A

identify edges/contours of the components in visual image

69
Q

MAJOR JOB of V2

A

identify disparities in the visual images presented by the two eyes - gives us depth perception

70
Q

Color vision in V1 is done by

A

blobs

71
Q

accurate color detection depends on input from

A

all three sets of cones

72
Q

_____ kinds of cones are triggered by any bright light

A

all three kinds of cones, because of the overlap in the sensitivities of opsins. certain types will just be activated more

73
Q

how does the brain arrive at color perception

A

uses the overlapping activity of the opsins

74
Q

MAJOR JOB of V4

A

complete processing of the color inputs

75
Q

without higher processing of the visual image, we could reconstruct the visual image but not

A 
name the image
copy the image
aim at the object in the image
recognize husband/wife/father/mother
we must rely on other areas of the cortex to interpret why the primary visual cortex and associated areas have done so far
76
Q

Dorsal pathway - think

A

motor

77
Q

Dorsal pathway - explained

A

the dorsal pathway leaving the occipital cortex relays information to the motor cotices and enables us to complete motor acts based on visual input - allows you to play catch

78
Q

Ventral pathway - think

A

recognition

79
Q

Ventral pathway - explained

A

the ventral pathway relays visual info to areas of the brain involved in higher processing of sensory inputs. The integration of visual input with other sensory input allows us to use that visual image to accomplish higher order functions, including naming the object and copying the object

80
Q

copying an object and naming/recognizing it are _____functions. damage to the temporal lobe can

A

separate

selectively impair one without hindering the other

81
Q

Similar or related objects are all coded for in

A

localized regions of the temporal lobe

82
Q

there is a specialized area for _________ (implications in autism)

A

recognizing human faces.

Neuro I (30 decks)

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