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The distance between two crests or troughs (peak to peak measurement)
Wavelength
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Filled with a jelly like fluid, refracts light onto the retina
Cornea
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Where the optic nerve leaves the eye, causes a blind spot
Optic Disk
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Where accomodation occurs
Lens
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Center of the retina, focused vision, where light falls when looking straight ahead
Macula
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Located at the center of the macula, dense # of photoreceptors
Fovea
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A fat lens is a result of ciliary muscles ______ and is used to see _____________.
-
A flat lens results when ciliary muscles _______ and is used for seeing ___________.
-
As aging occurs the lens _______, so it is harder for the lens to go _______, which impairs _________ vision.
-
Nearsightedness, also known as ________, is corrected by a ________ lens to reduce refractive power
-
__________, or farsightedness, is corrected by a ______ lens to add refractive power.
-
This condition is corrected by an asymmetric lens to compensate for the asymmetry of the eye's lens.
Astigmatism
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Increased fluid pressure in the eye causing optic nerve damage and eventually death resulting in blindness
Glaucoma
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The cones degenerate, central vision is lost, but peripheral vision remains due to the rods.
Macular degeneration
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Clouding of the lens and the lens must be surgically removed and replaced with a plastic one.
Cataracts
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3 layers of the Retina
- 1. Ganglion Cells
- 2. Bipolar Cells
- 3. Photoreceptors
-
Ganglion Cells contain
Amacrine cells
-
Bipolar Cells contain
Horizontal cells
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Peripheral vision, sensitive to light, high convergence and motion detection
Rods
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Central vision, sensitive to color, low convergence and fine discrimination
Cones
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Cones are more concentrated at the _____________
fovea
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Rods are concentrated more heavily ______________ the fovea
outside
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Rods and cones constantly regenerate this protein, because one it changes, it falls off of the receptor
opsin
-
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After about __ minutes in the dark, the rods are more sensitive than the cones
10
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On-center and off-center receptive fields ________ boundaries between light and dark.
enhance
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Ganglion cells responsible for fine detail. Have small receptive fields, sustained APs and color opponent cells
P-type
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Ganglion cells than are responsible for movement. Have large receptive fields, are sensitive to low contrast and have fast AP.
M-type
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Red/green type color opponent ganglion cells are ______ while blue/yellow are ________.
-
Why do we have parallel processing in the visual system?
Processing each bit of info sequentially would take too long and would be unreliable. Parallel processing is much faster.
-
mixed info from both visual fields
optic nerve
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nasal visual fields cross over at the
optic chiasm
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same information from one visual field travels along the
optic tract
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Why do we have binocular vision and what does it allow for?
Because the visual fields from both eyes overlap, creating depth perception in the center.
-
Can use two images taken from slightly different angles and present them next to each other, producing depth perception in once focused image
stereoposis
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2 pictures taken from slightly different angles and overlayed. One image is presented to each eye through color filtering glasses, which allows depth perception in a flat field.
3d stereoposis
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Responsible for pupillary light reflex and moves head to orient to a visual image.
Superior Colliculus
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__________ layers take info from P-type while ____________ layers take info from m-type
- Parvocellular
- Magnocellular
-
Lateral Geniculate Nucleus organization (dorsal to ventral)
P, K, P, K, P, K, P, K, M, K, M, K
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The major input to the LGN is the _________ cortex and the rest of the brain.
visual
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Project from layer 1 & 2 of LGN to layer IVCalpha
Magnocellular
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Project from layers 3-6 of LGN to layer IVCbeta
Parvocellular
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______ visual cortex cells respond strongly to a given orientation.
Simple
-
_______ visual cortex cells respond strongly to movement in a direction
Complex
-
5 things the primary visual cortex is responsible for.
- A complete map of the outside world in the brain
- Focuses on the middle of vision
- Focuses on contrast
- Tuned to straight lines in the environment
- Highly sensitive to motion and color
-
In the extrastriate cortex, the _______ is the 'where' pathway, so motion is analyzed.
________ is the 'what' pathway, detail and color are analyzed.
- Dorsal (moves to posterior parietal)
- Ventral (moves to inferior temporal cortex)
-
Damage to V4, loss of color vision (only see black and white), subjects describe the world as depressing and food as unappetizing and hard to taste.
Achromatopsia
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The eyes use the amount of light on the retina to help judge if an area is ________. All other colors are then compared to this baseline _______ color.
white
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Inability to identify common items, but may be able to copy drawing of items and draw items from memory
Visual Agnosia
-
Inability to recognize faces, including close family and themselves. Damage to IT and the Fusiform Face Area.
Prosopagnosia
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Damage to area MT of the brain; loss of ability to perceive motion, though perception of objects is intact
Motion Agnosia
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Perception of movement when none exists
Induced Motion
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Perception of motion in a stationary stimulus after viewing a moving stimulus. Occurs in area MT
Motion Aftereffect (or Waterfall Illusion)
-
Biological motion is the perception of motion related to living things. This involves the ________ __________ Sulcus
Superior Temporal
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When shown a still that suggests motion, people remember the motion as being ______ along than it actually is. This activates brain areas ___ and ____
-
Apparent and real motion occur in _____ & _______ (areas of visual cortex)
VI and MT
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