Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

TMTV > Lecture 1: the basics of vision > Flashcards

Lecture 1: the basics of vision Flashcards

1
Q

what is electromagnetic radiation

A

photons (or waves) traveling through space and carrying energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is electromagnetic spectrum

A

the range of all possible frequencies of electromagnetic radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is electromagnetic radiation characterized by

what is the formula

A

frequency and wavelength

v= c / lambda

c=speed of light
lambda=wavelenth
v=frequ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

energy is proportional to what

A

frequency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are the 4 major eye componenets

A

cornea
iris/pupil
crystallin lens (lens)
retina

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the refractive power of the cornea

A

~40D bc of snell’s law

  • constant hydration
  • transparent
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the job of the iris/pupil

A

iris: contracts and dilates
pupil: regulations retinal illumtination
- reducted aberrations
- increases depth and focus

range of pupil diameter 1-8mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is the refractive power of the lens? what is its function

A

~20D refractive power (relaxed)

  • necessary for accommodation
  • absorbs short wavelenth light

-chnage in power due to acc: 8D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

why does the lens change it’s refractive power

A

to maintain focus as the object distance varies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what happens when the lens accommodates

A

the ciliary muscle is contracted, the zonular fibers are relaxed, the tension on the lens capsule is less, the lens becomes thicker and therefore increases its power D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

how does the lens absorb short wavelength light?
why does it do it?
it comes at a cost, what happens

A

by producing chromophores

one possible explanation for this absorption is to protect the retina from high-energy, short wavelength light but comes at a cost=>CATARACTS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is presbyopia

A

the lens loses its ability to change its refractive power

  • eye cannot accommodate as a result
  • onset is ~40 years of age
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is a cataract

A

lens becomes opaque losing its transparency

  • as a result, the light reaching the retina is less than normal
  • when opacity increases above some point, VA decreases and the lens has to be replaced w/ an artificial intra-ocular lens (IOL)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

in catacts, what kind of damage is there? what kind of disorganization of cells

A

excessive oxidative damage

gross disorganization and disruption of fiber cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the retina the first stage of

A

information processing
~400micrometers
-several layers
5cm x 5cm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

how large is the fovea

A

1.8mm diameter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

how large is the foveal avascular zone

is there vasculature?

A
  1. 7mm diamter

- no retinal vasculature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

how large is the foveola
what kind of density, what does it contain
what kind of features does it have

A

0.3mm diamter
highest photoreceptor density (only cones)
thinnest part of retina
only outer retina features

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is macula lutea
what kind of protiens are here
where is max concentration at?
what role

A

yellow pigment
lutein, zeaxanthin and meso-zeaxanthin
maximum concentration in the fovea
protective role (AMD?)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what is in the inner retina

A 
ILM 
NFL 
ganglion cell layer
IPL 
INL
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is the outer retina

A 
OPL 
ONL 
OLM 
inner segemnts
outer segments 
RPE - bruch's
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

where are the photoreceptors (rods and cones)

A

ONL
OLM
Inner segments
outer segments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

if you keep the object size the same and double viewing dist, what happens to the visual angle

A

it is halved

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

if you keep the viewing dist the same and double the obj size then the visual angle is …..

A

doubled

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what happens if for an object of approx 1 degree of visual angle we double the viewing dist

A

the object occupies now 0.5 of visual angle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what happens if for an object of approx 1 degree we halve the viewing dist

A

the object occupies now 2 degrees of visual angle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what happens if we double the size of the object at approx 1 degree and double the viewing dist

A

the object is still 2 degrees of visual angle

28
Q

light travels from LGN and visual cortex to where

how does the signal travel

A

photoreceptors

signal travels from photoreceptors to LGN and visual cortex

29
Q

wehre does disk shedding/disk phagocytosis occur

A

the outersegments of RPE

30
Q 
for rods and cones respectively: 
count
peak density
time response
directionality
photopigment
temporal resolution
light sensitivity
spatial sensitivity
color visoin
adaptation
A 
120 mill, 6 mill
~20 degrees, absent from fovea, 0 degrees
-slow, fast
-no, sensitive to scattered: yes, sens to direct light
-rhodopsin, 3 pigments
-low 12Hz, high 60 Hz
-really high, low
-low, high
-no, yes 
-30 to 40 min, 5-8 min
31
Q

what is photopigment

A

a pigment that chemically reacts when it absorbs light (photons)

32
Q

what is the photopigment rods have

-what does it maximally absorb light at

A

rhodopsin

maximally absorbs light w/ 507 nm

33
Q

what are the 3 cone types

what do they absorb light at

A
  1. s cones: have cyanolabe which maximally absorbs at 426 nm
  2. m cones: chlorolabe which max absorbs at 530 nm
  3. l cones have erythrolabe which max absorb at 557nm
34
Q

after the photons are absorbed by photopigment, what happens to the photoreceptors

A

hyperpolarize (their membrane potential becomes negative)

-photoreceptors are directly connected w/ their electrical activiety transmited to horizontal cells and bipolar cells

35
Q

what is the receptive field of a neuron in the visual system

what is the receptive field of a single photoreceptor

A

the area that influences the neural activity of the cell

ex. receptive field of a single photoreceptor is their outer segment aperture

36
Q

a cell that is connected to multiple photoreceptors will have a receptive field of what?

A

rf equal to the sum of the receptive fields of all of the photoreceptors that it is connected to

37
Q

what are center-surround receptive fields?

A

they have a center that depolarizes to light and a surround that hyperpolarizes to light

38
Q

what does the center surround receptive field show

A

spatial antagonism or lateral inhibition

  • a light has the opposite effect in the surround than in the center
  • one part of the receptive field wnats to become active while the other part does not
39
Q

what are the two types of horizontal cells?
where do they receive input from

how do they transmit signal
where do they receive input from

A

H1: receive input mainly from both L and M cones
H2: receive input mainly from S cones but also from L and M cones

  • they don’t transmit any signal vertically only laterally
  • receive input from many cones
40
Q

what kind of surround are rod bipolar cells

A

no center surround RF (only ON)

41
Q

what are the 3 diff types of cone bipolar cells

A

midget bipolar cells
diffuse bipolar cells
s cone bipolar cells

42
Q

what is the size of midget bipolar cells in the fovea?
where do they receive their input from in their center RF ?
when do they become larger?
what does their RF ceive input from?

A

they are smaller in the central fovea and receive input in their center RF from a single L or M cone

they become larger in the periphery and receive input from multiple L or M cones in their center RF

their surround RF receives input from both L and M cones

43
Q

what are the three modern theories the diff rod to bipolar cell interactions

A
  1. rod to rod bipolar cell
  2. rod to cone bipolar cell through gap junctions w/ cones
  3. rod to cone ON and OFF bipolar cell
44
Q

how many types of amacine cells are there

how do they transmit their signal

A

22
transmit signal both vertically (from bipolar to ganglion cells)
and laterally (from bipolar to bipolar)

45
Q

how many ganglion cell types ar ethere

what are the 3 types of ganglion cells that are 70% of the total GC population

A

17

  1. midget: on and off center surround
  2. parasol: on and off center surround
  3. small bistratified: on and off

-high density

46
Q

what photopigment do ipRGCs (intrinsically photosensitive retinal ganglion cells) contain?
-what are they sensitive to

A

melanopsin

-sensitive at short wavelengths w/ a peak sensitivity at 488nm

47
Q

what is the significance of ipRGCs and what are complications that arise from them

A

sig: regulation of circadian rhythms
- reg of pupillary light reflex

complications: sleep disorders
- seasonal affective disorder (winter blues)

48
Q

what kind of light do midget GCs, parasol GCs, and small-bistratified GCs relate to

A

midget: red green
parasol: achromatic
small bi: blue yellow

49
Q

where does the signal from the GCs project to through the nerve fibers and via the optic disc

A

lateral geniculate nucleus (LGN)

50
Q

what are the cells and the pathways for
midget gcs
parasol gcs
small-bistratified gcs

A

midget: parvo cells (P) and parvocellular pathway
parasol: mango cells (M) and magnocellular pathway
small-bi: konia cells (K) and koniocellular pathway

51
Q

how do the pathways relate to in the LGN

A

remain segregate and anatomically distinct

52
Q

what are the 3 pathways considered to be componenets of

A

paraller retino-cortical processing

53
Q

what is the first structure where info from the LGN enters the visual cortex

A

primary visual cortex (V1)

54
Q

where is the primary visual cortex located

A

in the occipital lobe approx at the site of the inion

55
Q

how many layers does (V1) have?
which pathways project to 4C layer?
4Cb?
4Ca?

A
  • 6 layers w/ 1 being the most superfical
  • parvo and magnocellular pathway =4C
  • parvocellular -4Cb
  • magnocellular-4Ca
56
Q

what did hubel and wiesel propose

A

that the cortex is organized into ocular dominant columns and orientation selevtive columns

-now, more complex geometries

57
Q

information from V1 distributes to what other areas in the ____

A

occipital lobe like V2, V4, IT (inferotemporal, MT/V5)

58
Q

what are the 2 info pathways formed from the cortex

A

the ventral processing stream

the dorsal processing stream

59
Q

what is the ventral processing stream

A

object identification and recognition

60
Q

where is the dorsal processing stream

A

object’s spatial location visual guided behavior

61
Q

what is psychophysics

A

a sub discipline of psychology

  • internal (to the subject, soul) processes
  • the physical world
62
Q

waht is the fundatmentals to psychophysics

A

stimuls=>sensory system=> perception and response

P,R=f (stiumuls)

63
Q

threshold is reciprolly realted to what

A

sensitivity

64
Q

what are the psychophysical tests in clnic

A

VA
confrontational VF
VF
color vision tests

65
Q

what is the linear scale

what is the logarithmic scale

A

linear: a line which is divided into equal parts
log: a line which is divided into equal orders of magnitude (scale of #s w/ a fixed ratio expressed as power of 10)

TMTV (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions