Term
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Definition
| An inability to recognize visual objects that is niether a function of general intellectual loss or a loss of basic sensory abilities |
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Term
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Definition
| Patient is unable to recognize or draw simple shapes |
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Term
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Definition
| Patient is unable to recognize complex objects, but can recognize simple shapes and copy drawings of complex objects |
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Term
Visual Information Processing:
Cornea |
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Definition
- Membrane that protects eye
- Bends light toward lens
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Term
Visual Information Processing:
Iris
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Definition
- Colored part of eye
- Muscle - controls size of pupil
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Term
Visual Information Processing:
Pupil |
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Definition
- Opening in middle of iris
- Changes in size to let in different amounts of light
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Term
Visual Information Processing:
Lens |
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Definition
- Transparent structure
- Focuses, bends light as it enters the eye by changing its shape
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Term
Visual Information Processing:
Retina |
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Definition
- Neural tissue lining back of eyeball’s interior
- Contains the sensory receptors for vision: rods, cones
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Term
Visual Information Processing:
Fovea |
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Definition
Center of retina (cones only)
Sharpest vision |
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Term
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Definition
- Location where axons of retinal cells leave the eye and form the optic nerve
- No rods and cones
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Term
| Path of light wave through the eye (I) |
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Definition
Iris – controls the amount of light entering the eye by controlling the size of the pupil
Light passes through the lens and vitreous humor.
Lens – changes shape to focus the incoming light onto the retina (Accommodation)
Light is scattered slightly in passing through the vitreous humor, so the image falling back on the retina is not perfectly sharp.
A function of early visual processing is to sharpen the image.
Light strikes the retina. |
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Term
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Definition
Sensory Receptors (Retina)
Long, thin blunt sensory receptors of the eye that are highly sensitive to light, but not to color
Are primarily used for peripheral and night vision
About 120 million |
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Term
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Definition
- Short, thick pointed sensory receptors of the eye that detect color
- Responsible for color vision and visual acuity
- About 8 million
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Term
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Definition
| Specialized neurons in the retina that connect the rods and cones with the ganglion cells |
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Term
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Definition
- Specialized neurons that connect to the bipolar cells
- Their bundled axons form the optic nerve
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Term
Optic Pathways:
Optic Nerve |
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Definition
- The thick nerve that exits from the back of the eye
- Carries visual information to the brain
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Term
Optic Pathways:
Optic Chiasm |
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Definition
| Place where the optic nerve from each eye meet and partly cross over to the opposite side of the brain |
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Term
Optic Pathways:
Lateral Geniculate Nucleus |
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Definition
| Details and object recognition |
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Term
Optic Pathways:
Superior Colliculus |
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Definition
| Spatial localization of objects |
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Term
Optic Pathways:
Primary Visual Cortex |
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Definition
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Term
Visual Informatin Processing:
Path of light wave through the eye (II) |
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Definition
- The light energy activates rods and cones (retina).
- A photochemical process converts light into energy.
- Information from the rods and cones is collected by the bipolar cells, then the ganglion cells.
- The ganglion cell axons form the optic nerve.
- The optic nerves from the left and right eyes meet at the optic chiasm, then split apart.
- Once inside the brain, the fibers synapse onto cells in the primary visual cortex and other structures.
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Term
| On-off cells and off-on cells |
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Definition
Ganglion cells and cells of the lateral geniculate nucleus
[image] |
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Term
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Definition
| Respond positively to light on one side of a line and negatively to light on the other side |
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Term
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Definition
Respond positively to light in the center and negatively to light at the periphery, or vice versa |
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Term
| Response Patterns of Cells in the Visual Cortex |
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Definition
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Term
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Definition
| Spatial representations of visual features |
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