Lecture 8 Flashcards
what % of out brain processes visual information
50%
is the retina part of the cns or pns
cns
what is called when the lens becomes opaque
cateracts
this part of the eye regulate pupil size and is the color of the eye
the iris
this part of the eye is the most sensitive part of the body
the cornea
this part of the eye is the white part
the sclera
this part of the eye is located inside the eyelid
conjuctiva
what is the function of the extra ocular muscles
they help the eye move in different directions
where does light enter the eye
through the lens
after light hits the lens where does it go
to the retina
T/F images are seen rightside up in the retina
false, they are seen upside down
what will occur if the eyeball is either too long or too short
light rays will not focus properly
where does light enter through the eye
the lens
after light hits the lens where does it go
to the retina
are images seen upside down or rightside up in the retina
upside down
what will happen if the eye ball is either too long or too shote
light will not focus properly
nearsightedness is also known as hyperopia t/f
false ,nearsightedness is also known as myopia
t/f a short eyeball causes farsightedness
true
another name for farsightedness is
hyperopia
light rays from distant objects are …
parallel
light rays form far away objects are
divergent
are people with myopia able to see nearby or far away objects better
nearby
does a lot of nearwork cause the eyeball to elongate or shrink
elongate
what is a normal sized eyeball called
emmetropic
what muscles are responsible for controlling the lens curcature to properly focus the light on the retina
ciliary muscles
t/f the lens must change its shape in order focus light rays on distant objects
false
what is accommodation
the cilliary muscles contract to bulge the lens to refract the light properly
this part of the eye is where the blood vessels enter and exit the eye and where the retinal axons leave the eye
optic disk
name this part of the eye
a pit in the center of the eye
name this part of the eye : densest in photoreceptors and supports the highest acuity vision
fovea
t/f the optic disk lacks photoreceptors
true
what is the function of photoreceptors
they detect photons in their outer segments
which is more sensitive : rods or cones
rods
t/f rods can be responsive to one photon
true
which photoreceptors respond to waves of light
cones
what do the outer segments of rods and cones have
they have light absorbing chromophore retinal coupled to a protein called opsin
when retinal absorbs light what occurs
it chang es shapes
what does opsin activate
the g protein transducin
t/f photoreceptors have action potential s
false
what cause s changes in membrane potential in photoreceptors
light caused by graded potential
what does light activation cause in photoreceptors
hyperpolarization
photoreceptors are ______by light
hyperpolarized
when photoreceptors are depolarized what occurs
they release glutamate
is glutamate released in darkness or light
dark
what is released when photoreceptors are depolarized
glutamate
Are rods or Cones more sensitive to light at low levels
Rods
Do rods or cones saturate
Rods
Do rods or cones saturate
Rods
.?….. Are less sensitive to light but do not saturate
Cones
Are rods or cones associated with high acuity vision
Cones
What is high acuity vision
Vision with high detail
How many tyoes of Cones are there
3
Name the 3 types of cones
Short medium and long
The visual system determines color by comparing the……..of different types of cones
Activity
Normals humans have 3 cones . These are called
Trichromatic
Color blind people are
Dichromatic
Where is the retinal pigment epithelium found
Extends around the tip of photoreceptors
What is the functional of retinal pigment epithelium
Recycles the outer tips of photoreceptors
When are the retinal pigment epithelium generated
After light exposure
Are photoreceptors far away or close to light
Faraway
Are horizontal cells inhibitory
Yeah.
Do horizontal cells hyperpolarize or depolarize
Hyperpolarize
Do horizontal cells receive input from a lot of cells or only a few
A lot
Do horizontal cells send output to a lot of a little photoreceptors
Only a few
How are horizontal cells connected
They are connected by gap junctions
When the center is hyperpolarized is more or less glutamate released
Less
When the center is light but the surrounding is dark do the depolarize or hyperpolarize
Hyperpolarize
When both the center and surround cells are lit does hypolorization occur
No
When do horizontal cells cause greater cone response
When there are small spots of light or dark not big fields
do visual systems respond better to contrast or absolute light
Contrast
Where do bipolar cells receive input from
Photoreceptors
Do bipolar cells have action potentials or graded potentials
Graded
What 2 receptors do off center bipolar cells express
AMpa and kainate
When glutamate comes in contact with Off center bipolar cells what occurs
They are depolarized
What do on center bipolar cells express
MGlur
When off center bipolar cells come in contact with glutamate what occurs
They are inhibited. ( hyperpolarized )
On center cells ….. To spots of …..
Depolarize light
Off center cells depolarize to ….
Dark spots
Are amacrine cells excitatory or inhibitory
Inhibitory
What is the purpose of amacrine cells
Serve to regulate the activity of bipolar cells
T/f. Amacrine cells regulate the activity of bipolar cells
True
Retinal ganglion cells receive input from what two cells
Bipolar and amacrine
Do retinal ganglion cells have graded potentials
No
Do retinal cells have action potentials
Yeah
Do retinal cells respond best to spots of light or big fields of light or dark
Spots of light
Do on center cells respond best to white spots surrounded by dark or dark spors surrounded by white
White spots surrounded by dark
Which ganglion cells respond best to the photopigment melanopsin
Iprgc
What does iprgc stand for.
Intrinsically photoreceptive retinal ganglion cells
What is the. Name of the photopigment that iprgcs respond to
Melanopsin
T/f iprgc can detect light independent of photoreceptors
True
Name the cell that contributes to detection of ambient light levels ,light driven reflexes like controlling pupil size and. Circadian rhythm .
Iprgcs
The rgc axons exit the eye and begin what
The optic nerve
Name the cell whose axons exit the eye and begin the optic nerve
Retinal ganglion cells
What is unique about the optic chiasm
Some of the axons cross to the other side
Another word for crossing of axons is
Decusasstion
After the optic chiasm what are the axons called
The optic tract
All of the information from the right visual field is directed to which side of the brain
The left hemisphere
Where does decussation occur
At the optic chiasm
What is the function of suprachasmatic nucleus
Circadian rhythm
What is the function of the protectum
Pupillary
What is the function of the superior colliculus
Orients movements of the head and eye
What is the function of the dorsal lateral geniculate nucleus of the thalamus
It is involved in processing
Which axons go to the primary visual cortex
Dorsal lateral geniculate nucleus
Connection from the dlgn to the cortex is called …
Optic radiation
Do v1 neurons respond well to light
No
V1 neurons respond best to what
Moving oriented bars in a specific area of space
Why do v1 neurons respond best to bars
Because 2 or more inputs are summed together
T/f v1 neurons do not care about bar orientation
False, they care. Straight up and down is best
What is a tuning curve
Shows which stimulus an individual cell responds to best.
In humans neurons with similar orientations are clustered together in things called
Orientation columns
How is v1 organized
Retinotopically
Where is the first place in the visual system that has cells that receive information from both eyes
V1
Define ocular dominance
The degree to which a cell favors one eye over the other
T-/f cells with similar occular dominance do not cluster near each other
False
What is an ocular dominance column
Cells with similar occular dominance cluster together
T/f ocular dominance is plastic
True
Is ocular dominance always plastic
No only during the critical period
T/f every neuron in v1 has a set if characteristics that it responds to best
True
