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31 Cards in this Set
- Front
- Back
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What path does light takes when it enters the eye |
Cornea to the aqueous humor then through the lens (to get to the lens it must pass through the pupil). After the lens it will enter the vitreous chamber where it will be refracted for the fourth time at the vitreous humor. After traveling through the vitreous chamber the light emitted will be brought into focus on the retina |
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Emmetropia |
The condition in which there is no refractive error, because the refractive power of the eye is perfectly matched to the length of the eyeball |
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Diopter |
A unit of measurement of the optic power of a lens. It is equal to the recipricol of the focal length, in meters. A 2-diopter lens will bring parallel rays of light into focus at 1/2 meter (50cm) |
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What 3 pairs of nerves move the eye? |
Oculomotor, abducens and trochlear |
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7 nerve pairs that carry sensory information |
olfactory, auditory, optic, vagus, trigenial, glossopharyngeal and facial *olfactory, auditory and optic are strictly sensory |
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Which lengths are refracted more, long or short? |
Short wavelengths are refracted the most Long wavelengths are least refracted |
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What does the sharpness of an image depend on with respect to parts of the eye? |
Cornea 2/3 and lens 1/3 |
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4 Factors that affect Contrast Sensitivity Function (CSF)? |
Adaption level of the eye, the temporal modulation of the targets, age and refractive state of the subject |
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What type of processing is conducted in the magnocellular layer vs. the parvocellular layer? |
The magnocellular layer responds to fast moving objects whereas the parvocellular responds to finer detail of stationary targets |
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Which cells have an all or nothing action potential and which have a graded potential? |
amacrine and retinal ganglion = all or nothing horizontal, photoreceptors and bipolar = graded potential |
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What is the temporal response from midget ganglion cells (p-cells) and Parasol ganglion cells (m-cells)? |
P-cells have a sustained response lasts entire time light is on or off RF m-cells have a transient response, brief response at on/off set of of light in RF |
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What does the Landolt C measure? |
Visual acuity on the fovea |
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What does it mean if someones snellen ratio is 6/3? |
The person can read at 6 m what normal people can read at 3m |
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What is the difference between Photopic and Scotopic vision? |
Photopic is cone mediated vision in bright light Scotopic is rod mediated vision at dim light |
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What is the Rod response in bright light |
Rod response saturates at bright light |
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What is the cone response in dim light |
Cones arent very sensitive in dim light compared to rods |
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What is Dark adaption? |
Increase in sensitivity in the dark when we switch from photopic to scotopic |
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What is the contrast equation? |
(L_max - L_min)/(L_max+L_min) |
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What are the 4 parameters that can be manipulated in grating stimuli? |
Orientation, Spatial frequency, contrast and phase |
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Why is there a fall-off in sensitivity on the CSF at low spacial frequency? |
Because fewer neruons are tuned for low spatial frequency and experimental design |
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Definition of receptive field? |
the receptive field of a neuron is the region in space in which the presence of a stimulus alters the neurons firing ability |
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Orientation tuning |
the tendency of neurons in the striate cortex to respond optimally to certain orientations and less to others |
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What layers in the v1 correspond to the layers in the LGN (ie magnocellular, parvocellular and koniocellular)? |
Magnocellular is 4c-alpha Parvocellular is 4c-beta Koniocellular is layer 2/3 layer 4a? |
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What layer in the v1 are binocular neurons found? |
layers 2/3, 5 and 6 |
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optic radiations |
connect LGN to optic cortex |
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Optic Chiasm |
splits the optic nerves at the nasal passage |
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What does left V1 damage below calcarine fissure produce? |
Blindspot on the upper right visual field |
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Quadrantanopia |
Damage to half of V1 in one hemisphere produces quadrantanopia (blindness in the corresponding quadrant of the VF) |
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Hemianopia |
Damage to the entire V1 in one hemisphere produces hemianopia (blindness in the contralateral half of the VF) |
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Why is adaptation is good in the real world? |
- higher detectability and discriminability of new novel stimuli - sensitivity matches prevailing conditions - metabolic saving: reducing the number of active neurons and weaker responsiveness saves metabolic energy |
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What happens when the Eustachian Tube fails to open up? |
Negative pressure builds up, increasing the stiffness in the middle ear transmission system (more for low frequencies sounds) |
