Lecture 14 Colour Vision
Call Kai
Learn
Practice Test
Spaced Repetition
Match
Flashcards
Knowt Play1/104
There's no tags or description
Looks like no tags are added yet.
105 Terms
to understand colour, what properties do we need to understand
light
the perception of colour is a __ awareness
psychological
colour is NOT a __ property of objects
physical
what characteristics does light have
a wave and a particle
what is the perception of colour dependent on
wavelength of light
what colour in the visible spectrum has the largest wavelength
red
what colour in the visible spectrum has the smallest wavelength
violet
wavelength of visible spectrum
400-700 um
what is light absorbed by
photoreceptors
which photoreceptor detect dim light
rods
which photoreceptor is responsible for scotopic vision
rods
which photoreceptor contains rhodopsin
rods
peak wavelength for rhodopsin
507 nm
rods is responsible for detection of what
dim light
rods corresponds to which vision
scotopic vision
what is the light-sensitive pigment protein found in rods
rhodopsin
which photoreceptor is responsible for high resolution and colour vision
cones
which photoreceptor has phototopic vision
cones
which photoreceptor has chromophore and opsin
cones
cones is responsible for detecting what
high resolution and colour vision
cones is responsible for what vision
phototopic vision
Each photoreceptor contains an opsin which is most activated by?
a specific wavelength of light
how is a photopigment formed
when an opsin binds to a chromophore
where does maximum spectral sensitivity occur
at maximum wavelength
what is Trichromatic Theory
colour information is coded by three types of cones, and the relative activation of each cone codes for every colour
what is the trichromatic theory based on
principle of univariance
what is principle of univariance
a single photoreceptor (such as a rod or an individual cone) produces a one-dimensional neural response that depends only on the total number of photons absorbed
how do we name different cones
by the maximum wavelength of their photopsin
in which cone do we find Cyanolabe
S-cone
in which cone do we find chlorolabe
M-cone
in which cone do we find erytholabe
L-cone
maximum wavelength of cyanolabe
426 nm
maximum wavelength of chlorolabe
530 nm
maximum wavelength of erytholabe
560 nm
which photopsin correspond to the shorter wavelength
Cyanolabe
which cone correspond to the medium wavelength
Chlorolabe
which photopsin correspond to the longer wavelength
Erytholabe
what colour is Cyanolabe sensitive to
blue
what colour is Chlorolabe sensitive to
green
what colour is Erytholabe sensitive to
red
where are cones concentrated in
center of fovea
where are L and M cones distributed in the fovea
randomly
small central zone in the fovea lacks which cone
S-cone
what is the Opponent Process Theory
the retina siphons colour information through three channels with two opponent pairs, which allow us to perceive colour uniformly
where does the relative response for each channel with two opponent pairs first appear in
horizontal cells in the retina
after appearing in the horizontal cells in the retina, where do each channel of opponent pair go through
dLGN (dorsal lateral geniculate nucleus)
what are the three opponent pairs in the opponent process theory
Red vs green
Blue vs yellow
Black vs white
where is the colour information ultimately coded
in area V4 of the occipital lobe
what is the V4 area in occipital lobe specialized in
colour perception, colour information, and form/shape recognition
describe this theory: the retina siphons colour information through three channels with two opponent pairs, which allow us to perceive colour uniformly
Opponent Process Theory
describe this theory: colour information is coded by three types of cones, and the relative activation of each cone codes for every colour
Trichromatic Theory
stroke in the V4 of occipital lobe will cause what
cerebral achromatopsia
what is cerebral achromatopsia
deficiency in colour perception
what is Colour vision defects classified upon
presence and function of their S, M, and L cones
how many cone cells does a trichromat have
three
how many cone cells does a dichromat have
two
how many cone cells does a monochromat have
one
if a person is missing or have a dysfunctional cone, which cone is it usually
S-cone
what is Trichromacy
All three types of cones present and have photopigment with normal maximum wavelength
what is Anomalous trichromacy
All three types of cones are present but one cone contains photopigment with a shifted maximum wavelength
what is the term for normal colour vision
trichromacy
what is the term for mild colour vision defect
Anomalous trichromacy
what is the term for moderate colour vision deficiency
dichromacy
what are the three types of trichromat
Protanomalous, Deuteranomalous, Tritanomalous
for a Protanomalous trichromat, what is the dysfunctional cone
L-cone
for a Deuteranomalous trichromat, what is the dysfunctional cone
M-cone
for a Tritanomalous trichromat, what is the dysfunctional cone
S-cone
for Protanomalous trichromat, where is the maximum wavelength shifted
shifted down
for Deuteranomalous trichromat, where is the maximum wavelength shifted
shifted up
for Tritanomalous trichromat, where is the maximum wavelength shifted
shifted up
what is the vision anomaly that has one missing cone
dichromacy
three types of dichromats
Protanope, Deuteranope, Tritanope
for a Protanope, what cones are we missing
L-cone
for a Deuteran, what cones are we missing
M-cone
for a Tritanope, what cones are we missing
S-cone
what is dichromacy
moderate colour vision deficiency where one cone is missing
what is Monochromatism
“very severe” colour deficiency
the term for “very severe” colour deficiency
monochromatism
what is the usual cone affected for monochromatism
S-cone
what is the decreased VA for rod monochromatism
20/200
why are there more males than females with colour vision deficiencies
due to sex-linked (x-linked recessive) nature of condition
what are some ocular pathology associated with colour vision defects
optic neuritis, age-related macular degeneration, cataracts, retinal dystrophies, RPE dystrophies
name the colour vision tests
Pseudoisochromatic Plate Testing, Colour Arrangement Tests (Farnsworth), Nagel Anomaloscope
most common colour vision test
Pseudoisochromatic Plate Testing
what methods do we use for Pseudoisochromatic Plate Testing
Ishihara, HRR
why is Pseudoisochromatic Plate Testing most commonly used
inexpensive, simple, quick
Pseudoisochromatic Plate Testing cannot differentiate between what
dichromat vs anomalous trichromat
Ishihara can detect what colour defects
red green
HRR can detect what colour defects
red green and blue yellow
HRR can CLASSIFY between what defect
Protan vs Deutan vs Tritan
HRR is unable to discern between what
dichromat vs anomalous trichromat
colour arrangement tests cannot differentiate between what
dichromat vs anomalous trichromat
why is colour arrangement tests not preferred
time consuming
which test is unable to distinguish cones or if cones are dysfunctional
colour arrangement tests
when is Nagel Anomaloscope used
research setting
which test can differentiate between Dichromat vs Anomalous Trichromat
Nagel Anomaloscope
how far should you hold the plates for HRR
75 cm
why should we use incandescent bulb instead of fluorescent lights for HRR
because those lights can wash our colours
when is Daylight Illuminator used with HRR
research only
how do we calculate defect with HRR
Column with MOST checkmarks