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58 Cards in this Set
- Front
- Back
Beyond the immediate area of the circle of Willis, the optic tract is usually supplied by the the _
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anterior choroidal artery.
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The lateral geniculate nucleus itself is primarily supplied by the _, a branch of the posterior cerebral artery.
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lateral posterior choroidal artery
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The optic radiation or geniculocalcarine tract project between the _ and _
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lateral geniculate nucleus and primary visual cortex
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The projection for the upper half of the visual field is called _, it travels forward and over the _.
The lower half of the visual field projection goes directly _, over the _ |
Meyer's loop, the inferior horn of the lateral ventricle.
directly posteriorly over the atrium of the lateral ventricle. |
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Meyer's loop projections are subject to lesions of what artery?
Those more medially placed fibers are sensitive to lesions of what artery? |
Middle cerebral artery
Posterior Cerebral artery |
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Beyond the geniculocalcarine tract, most of visual cortex is supplied by the _ artery
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posterior cerebral artery.
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Localized damage in the retina can produce visual field deficits that are _
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inverted and switched left to right.
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Glaucoma typically arises from disruption of the __
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production or drainage of aqueous humor in the anterior chamber, and may result in increased intraocular pressure.
This pressure is transferred to the back of they eye where the optic disc is sensitive to damage |
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Retinal separation occurs between the _ and _, typically at the periphery of the retina.
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pigment epithelium and photoreceptor layer
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Retinal detachment is perceived as _, _ and _ in one eye.
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bright flashes, increases in floating bodies, and a partial loss of vision,
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The _ is the region of highest visual acuity
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fovea
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_ form is the most common type of macular degeneration.
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dry form.
may be due to hereditary factors, cardiovascular disease, light exposure, and nutritional causes |
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Transient blindness on the affected side that is seen as a window shade going down over the eye describes what condition?
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amaurosis fugax
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The right half of the visual field in (right,left,each) eye gets routed to the left hemisphere
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each
And the left half of the visual field in each eye gets routed to the right. |
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Visual deficits in both eyes suggest...
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a lesion of the visual system either in the optic chiasm or beyond it toward the CNS.
*A possible exception is very proximal lesions of the optic nerve can involve optic nerve axons from the chiasm that arise from nasal retina of the contralateral eye. |
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Lesions of the center of the optic chiasm disrupt the axons crossing from the _
This produces (bilateral/ipsilateral/contralateral) deficits in the _ visual field or _ |
nasal retina.
bilateral temporal bitemporal hemianopia |
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A lesion of the _ artery, affecting the optic tract produces homonymous hemianopia, which is where axons from the _retina of the contralateral eye and the _ retina of the ipsilateral eye are interrupted
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anterior choroid artery
nasal from the contralateral temporal from the ipsilateral |
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The inferior visual field projects to the _ retina, and the _ bank (of the calcarine sulcus).
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superior retina and superior bank
this is opposite for superior visual field |
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Lesions of meyer's loop, with is the most common visual complication of _ artery strokes, produces _
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middle cerebral artery;
superior homonymous quadrantanopia |
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Lesions that include primary visual cortex will produce _
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contralateral hemianopsia with macular sparing.
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With homonymous hemianopia, the closer the defect is to the chiasm the more _the left and right visual fields maps will be; the more posterior the lesion (toward occipital lobe) the more _the visual field defect.
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dissimilar , congruous
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TheThe eye consists of 2 fluid filled chambers, the area in front of the lens, that is filled with _and a chamber behind the lens, that is filled with _
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aqueous humor
vitreous humor |
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Regarding lens accomodation, the lens becomes more _ shaped when viewing an object that is close than 20 ft, this action is achieved by the _ muscle.
The loss of the accomodation reflex with age is called _ |
round
ciliary presbyopia |
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If the eye is too short (or squat), it results in _.
If the eye is too oblong, it results in _ |
hyperopia, or far sightedness
myopia, or near-sightedness |
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The inner layer of the eyeball is the _. This is where light is absorbed and transduced into an electrical signal
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retina
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Transduction is accomplished by photoreceptors on the _ layer of the eye.
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most posterior
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Rods are sensitive to _, and are located in the _ region of the retina. Rods contain photo-pigment containing _.
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dim light (night vision, scotopic vision) - they can not differentiate color.
Located in the non foveal region of the retina, and contain rhodopsin (Vit A) |
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Cones or rods are more sensitive to light
Cones or rods are more prevalent in the eye |
rods
rods |
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Cones are mostly found in the _ region
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foveal
The fovea is the region of the eye with the highest visual acuity |
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At the center of the fovea is the _, a 100 um wide area with specialized cones called _ and corresponding bipolar cells and ganglion cells
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foveola; midget cones
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Cones have different pigments, _ which are sensitive to different frequencies of light.
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iodopsins,
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In the dark, rods are depolarized to -40mV, and they release _ to 2nd order cells
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glutamate
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Under illumination, when photoreceptor glutamate ↓, on-bipolar cells are _
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disinhibited.
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Horizontal cells are (inhibitory/excitatory)
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inhibitory...they release GABA
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If the subject is in the dark, half the bipolar cells will be firing vigorously, those are the (on/off)center, (on/off) surround
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Off center, on surround
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Lateral inhibition mediated by horizontal cells is part of the mechanism responsible for _
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Mach lines (seeing the edge in light vs dark)
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_ and _ cells synapse on ganglion cells.
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Bipolar and amacrine cells
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_ cells are the only retinal cells that have voltage gated sodium channels, and the only cell type that generates action potentials.
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Retinal ganglion
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Largest RGC population are the _ cells
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alpha cells (physiologic Y or M)
they receive Input from peripheral rods. I.e. involved in scotopic vision they are Large cells with large receptive fields |
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beta RGC have input from _, _ receptive fields, and are used for _ vision
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cones; small; high resolution vision
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Retinal ganglion cell axons within the retina are unmyelinated until they pass through the _, after which they become myelinated in the optic nerve
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sclera
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Retinal ganglion cells primarily contact the _ of the thalamus
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lateral geniculate nucleus of the thalamus
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Layers 1 & 2 of the lateral geniculate are called the _ layers, receive input from _ type RGCs with receptive fields that receive input primarily from _ .
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magnocellular
large alpha (Y) rods |
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Layers 3-6 (aka _ ) receive input from _type RGCs with receptive fields that receive input from _and process _
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parvocellular layers;
smaller, beta (X) cones high acuity color visions. |
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As part of the distribution of visual fields, axons in the temporal retina are distributed to the (ipsilateral/contralateral) lateral geniculate nucleus in layers _,_, and _
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ipsilateral
2, 3, and 5. |
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As part of the distribution of visual fields, axons in the nasal retina are distributed to the (ipsilateral/contralateral) lateral geniculate on layers _,_ and _
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contralateral
1, 4, and 6. |
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The neurons of the lateral geniculate project to the ipsilateral visual cortex as a bundle of axons, the _
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optic radiations (geniculocalcarine tract).
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The optic radiations have two primary bundles: one that projects to the _and the other, Meyer’s Loop, going to the _
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superior bank of the calcarine sulcus,
inferior bank of the calcarine sulcus |
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Meyer's loop runs downward and backward over the _ on it's way to the inferior bank of the calcarine sulcus. The inferior banks represent the (superior/inferior) visual fields
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lateral ventricle
superior |
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Regarding the retinotopic map; Peripheral fields are located _, Central vision -the macula and fovea –are represented more _
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rostrally
caudally toward the occipital pole. |
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Due to a white band called the band of Gennari, primary visual cortex is referred to as _
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Striate cortex.
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Regarding the retinotopic map of the LGN, peripheral fields are located _, while central vision (macula and fovea) is represented _
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rostrally
caudally |
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There are blob zones dispersed within the ocular dominance and orientation columns that process only _. These are prominent in what layers?
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color information.
layers II and III (Not IV) |
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The M stream arises from the _ areas of the LGN, carrying information from RGCs with _ receptive fields. The route for this stream is...
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magnocellular areas; large receptive fields.
V3 sub region of 18 -> middle temporal area (MT V5) -> Posterior parietal (7a) |
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_ appears responsible for processing “where” objects are in the visual field, including position, motion, to some extent depth, and other spatial information.
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Magnocellular stream
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The P stream receives information from the _ areas of the LGN, it is the "_" stream, and processes _ and _
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Parvocellular
"what" color and shape |
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The pathway for the P stream is...
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Outputs from V2 to V4 subregion of area 19, to the inferior temporal region, and then areas 20, 21, and 37
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The _ is primarily involved in depth perception.
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parvocelluar stream
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