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What is the binocular zone?
Central region seen by both eyes
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What are the monocular zones (crescents)?
Peripheral regions seen only by ipsilateral eye
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What are hemifields?
Divisions of the visual field into nasal and temporal halves
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What are quadrants?
Divisions of the hemifields into upper and lower parts
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How does the lens effect the projection of the visual field on the retina?
Inverts, reverses projection
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What are M Cells?
1. Location in retina?
2. Input source?
3. Sensitive to?
Large ganglion cells
- 1. Periphery
- 2. Rods and cones
- 3. Movement, orientation, high contrast images
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What are P Cells?
1. Location in retina?
2. Input source?
3. Sensitive to?
Small ganglion cells
- 1. Centrally
- 2. Cones (mostly)
- 3. Color coding, fine detail
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1. Describe the decussation that takes place at the optic chiasm
2. What is the resulting information in each optic tract?
1. Fibers from the NASAL halves of each retina cross
2. Info from the Contralateral Visual Hemifield
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What are the targets of axons that make up the optic tract?
- Lateral Geniculate BodySuperior Colliculus - reflex responses
- Pretectal Area - pupillary light reflex
- Suprachiasmatic Hypothalamic Nucleus - circadian rhythms
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In which layers of the LGB do axons from the ipsilateral eye terminate?
2, 3, 5
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In which layers of the LGB do axons from the contralateral eye terminate?
1, 4, 6
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What is Binocular Input and where is it located?
- Information from both eyes converges on single cells
- Only in the visual cortex
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M Cells project to which LGB layers? What is the name for these layers?
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P Cells project to which LGB layers? What is the name for these layers?
- 3, 4, 5, 6
- Parvocellular layers
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Along what path do LGB axons course to the primary visual cortex?
Optic Radiation (Geniculocalcarine Tract)
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Information from the lower quadrant of the contralateral visual hemifields:
1. LGB origin?
2. Course?
3. Target?
- 1. Dorsomedial LGB
- 2. Pass directly through internal capsule
- 3. Superior bank of the calcarine sulcus
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Information from the upper quadrant of the contralateral visual hemifields:
1. LGB origin?
2. Course?
3. Target?
- 1. Ventrolateral LGB
- 2. Meyer's loop - lateral to inf. horn of lat. ventricle
- 3. Inferior bank of the calcarine sulcus
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What are the names associated with the Primary Visual Cortex?
- Area 17
- Visual Area 1 (V1)
- Striate Cortex
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What would be the cause of Complete blindness in the right eye?
Lesion in the Right Optic Nerve
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What would be the cause of Bilateral Heteronymous Hemianopsia?
Lesion in the Optic Chiasm
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What is bilateral heteronymous hemianopsia?
- Loss of both peripheral fields
- aka Tunnel vision
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What would be the cause of Left Homonymous Heminopsia?
Lesion of the Right Optic Tract
OR
Lesion of the Right Optic Radiation
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What is homonymous heminopsia?
- A loss of one visual hemifield
- ex. right side blindness in both eyes
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What would be the cause of Left Superior Quadrantanopsia?
Temporal lobe lesion affecting the Meyer's Loop or destruction of lingual gyrus
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