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Questions and Answers
Explain the difference between trichromatic coding and opponent-process coding in terms of color perception.
Explain the difference between trichromatic coding and opponent-process coding in terms of color perception.
Trichromatic coding suggests that our perception of color is based on the relative activation of three types of cones sensitive to different wavelengths of light (red, green, and blue). Opponent-process coding, on the other hand, proposes that color perception arises from opposing pairs of color channels, such as red-green, blue-yellow, and black-white. These opposing channels work in a way that the activation of one channel inhibits the activation of its counterpart, leading to the perception of specific colors.
What is color constancy and how does the Retinex theory explain it?
What is color constancy and how does the Retinex theory explain it?
Color constancy refers to our ability to perceive the color of an object as relatively constant despite changes in illumination conditions. The Retinex theory proposes that the cortex compares the overall color across the retina, taking into account the surrounding colors, to deduce the true color of an object, maintaining its perceived color even under varying lighting.
How do the responses of the three types of cones contribute to our perception of different colors?
How do the responses of the three types of cones contribute to our perception of different colors?
The perception of color arises from the unique combination of activation levels across the three types of cones. Each cone type is maximally sensitive to a different wavelength of light. The relative activation of these cones, based on the wavelengths present in the light, determines the color we ultimately perceive.
What is the role of bipolar cells and ganglion cells in color vision?
What is the role of bipolar cells and ganglion cells in color vision?
What is color vision deficiency and how does it affect color perception?
What is color vision deficiency and how does it affect color perception?
What is the name of the structure in the eye that helps focus light on the retina?
What is the name of the structure in the eye that helps focus light on the retina?
What is the name of the clear, fluid that fills the space between the lens and the retina?
What is the name of the clear, fluid that fills the space between the lens and the retina?
What is the name of the transparent outer layer of the eye that helps to focus light?
What is the name of the transparent outer layer of the eye that helps to focus light?
What is the name of the colored part of the eye that controls the amount of light entering the eye?
What is the name of the colored part of the eye that controls the amount of light entering the eye?
What is the process called that allows the eye to focus on objects at different distances?
What is the process called that allows the eye to focus on objects at different distances?
What are the three main layers of cells in the retina?
What are the three main layers of cells in the retina?
What is the name of the location on the retina with the sharpest visual acuity?
What is the name of the location on the retina with the sharpest visual acuity?
What is the name of the point on the retina where the optic nerve leaves the eye, creating a blind spot?
What is the name of the point on the retina where the optic nerve leaves the eye, creating a blind spot?
What are the two primary types of photoreceptor cells in the retina?
What are the two primary types of photoreceptor cells in the retina?
What is the name of the light-sensitive pigment found in photoreceptor cells?
What is the name of the light-sensitive pigment found in photoreceptor cells?
What is the name of the molecule that is involved in the photopigment's response to light?
What is the name of the molecule that is involved in the photopigment's response to light?
What happens to the photoreceptor when light is absorbed by its photopigment?
What happens to the photoreceptor when light is absorbed by its photopigment?
What type of neurotransmitter is released by the photoreceptor, and what effect does it have on the bipolar cell?
What type of neurotransmitter is released by the photoreceptor, and what effect does it have on the bipolar cell?
How does light absorption by the photoreceptor ultimately lead to the excitation of the ganglion cell?
How does light absorption by the photoreceptor ultimately lead to the excitation of the ganglion cell?
What type of visual disorder involves the destruction of the fovea and its surrounding area, creating a blind spot on the retina?
What type of visual disorder involves the destruction of the fovea and its surrounding area, creating a blind spot on the retina?
Flashcards
Trichromatic Coding
Trichromatic Coding
The theory that color perception arises from the responses of three types of cones sensitive to different wavelengths.
Opponent Process Coding
Opponent Process Coding
A theory by Ewald Hering that explains color perception through opposing pairs: red vs. green, yellow vs. blue, and black vs. white.
Color Constancy
Color Constancy
The ability to perceive colors consistently under varying lighting conditions by comparing overall color across the retina.
Color Vision Deficiency
Color Vision Deficiency
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Retinex Theory
Retinex Theory
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Sensory Processes
Sensory Processes
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Reception
Reception
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Transduction
Transduction
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Coding
Coding
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Accommodation
Accommodation
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Fovea
Fovea
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Photoreceptors
Photoreceptors
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Rods and Cones
Rods and Cones
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Macular degeneration
Macular degeneration
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Retinitis pigmentosa
Retinitis pigmentosa
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Photopigment
Photopigment
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Hyperpolarization
Hyperpolarization
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Visual Pathway
Visual Pathway
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Color Perception
Color Perception
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Ganglion Cells
Ganglion Cells
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Study Notes
Sensory Systems Overview
- Sensory systems rely on reception, transduction (converting stimulus energy to neuronal signals), and coding (linking stimulus features to neuronal activity).
- Visual system is used as an example to describe the processes.
Anatomy of the Eye
- Lens: Focuses light.
- Vitreous Humor: A transparent jelly-like substance filling the eye.
- Cornea: Transparent outer layer of the eye, responsible for refraction.
- Iris: Controls the amount of light entering the eye.
- Accommodation: Changing lens shape to focus on varying distances.
- Retina: Contains photoreceptors and various other cells responsible for detecting light.
- Optic Disk: Where optic nerve exits the eye, creating a blind spot.
- Optic Nerve: Carries visual information from the retina to the brain.
- Fovea: Region of the retina with the highest visual acuity.
- Peripheral Vision: Better at detecting dim light.
Cellular Components of the Retina
- Photoreceptors (Rods and Cones): Specialized cells sensitive to light.
- Rods: High sensitivity to dim light (120 million).
- Cones: High sensitivity to color and detail (6 million).
- Bipolar Cells: Relay information from photoreceptors to ganglion cells.
- Ganglion Cells: Generate action potentials, transmitting signals to the brain via the optic nerve.
- Amacrine Cells: Modify signals between bipolar and ganglion cells.
Vision Transduction
- Photopigment: (retinal + opsin) Chemical that absorbs light.
- Photoreceptor Response: Light causes a hyperpolarization in photoreceptors, reducing neurotransmitter release.
- Bipolar and Ganglion Cells: Bipolar cells are excited by the reduced inhibition, while Ganglion cells receive the signal and produce action potentials.
Visual Field
- The entire area that can be seen by the eye.
Color Vision
- Trichromatic Theory: Three types of cones, each maximally sensitive to different wavelengths (red, green, blue).
- Opponent-Process Theory: Color perception based on opponent pairs (red-green, blue-yellow).
- Color Constancy: Ability to perceive colors consistently despite varying lighting conditions.
- Retinex Theory: cortex compares overall color across the retina in order to judge color.
Visual Processing in the Brain
- Visual information from the optic nerve travels to specific areas of the brain for further processing.
- Areas like V1, V2, V4, and the inferior temporal cortex are involved in visual tasks such as colour, motion, form and shape identification.
Visual Disorders
- Macular Degeneration: Damage to the fovea, leading to loss of central vision. Common in older individuals.
- Retinitis Pigmentosa: Genetic disorder causing progressive loss of rods, eventually impacting cones.
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