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17 Cards in this Set
- Front
- Back
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Where is the area of highest visual acuity on the retina? What is the primary type of photoreceptor cell in this area?
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*fovea
*cones |
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What is the cause of retinitis pigmentosa?
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*a mutation in rhodopsin causes misfolding and a new tertiary structure
*the photoreceptor is no longer able to transduce light |
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What symptoms are seen in retinitis pigmentosa?
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*deposits of pigment on retina
*general degeneration of retinal tissue *disruption of vision, especially in the periphery |
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How many types of cone cells are there? How are they different?
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*3
*based on peak wavelength sensitivity (blue, green, yellow) |
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What type of photoreceptor provides most of the vision at very low light?
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Rods
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What happens to the photoreceptor cell when it is hit by light?
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It is hyperpolarized and stops releasing neurotransmitter.
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What happens to the bipolar cells when light hits the photoreceptor cell?
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*this varies by cell
*some bipolar cells are activated by the cessation of neurotransmitter *some are inhibited |
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What is the spatial receptive field of an RGC?
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The region of the visual field where light can elicit action potential activity from that RGC.
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Is the size of the spatial receptive field constant for all RGC's? Why or why not?
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*no, it varies by retinal position
*each RGC acquires information from a varying number of photoreceptors *the more photoreceptors that feed into a single RGC, the larger the spatial receptive field |
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What is luminance? How can it be quantified?
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*the amount of light hitting a surface
*the number of photons |
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What is contrast? How can it be quantified? What can improve perception of contrast?
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*a perceived difference in brightness
*can't be quantified - no absolute fidelity with number of photons *perceived in a relative context *addition of color |
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How do cells in the center vs. the surround of the receptive field differ?
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*their response to light - i.e. inhibitory or excitatory for RGC when hit with light
*the color to which they are most sensitive |
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What type of vision do P cells provide? Describe the size of their receptive fields. What are their responses like?
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*form and shape, color and acuity
*small receptive fields *brisk and sustained responses |
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What kind of vision do M cells provide? Describe the size of their receptive fields. What kind of responses do they generate?
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*perception of movement
*large receptive fields - extensive dendrite array contacts many photoreceptors *fast and transient responses |
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What layers of the LGN receive input from the P cells? What are these layers called?
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*6,5,4,3
*parvocellular |
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What layers of the LGN receive input from the M cells? What are these layers called?
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*1,2
*magnocellular |
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The right LGN receives input from the right eye at which layers? Input from the left eye?
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*right eye: 5,3,2 (ipsilateral)
*left eye: 6,4,1 (contralateral) |
