16 Questions
What physiological mechanism enables better detection of edges in vision?
Lateral inhibition
Where is the left visual field information from both eyes processed?
In the right half of the brain
What is the role of the Lateral Geniculate Nucleus in visual processing?
Relay station within the thalamus
Which is an example of a phenomenon supporting the center-surround model of vision?
Mach band illusion
What triggers a voltage change across the cell membrane in photoreceptors?
Absorption of light by rhodopsin
Which statement best describes the function of rhodopsin in the visual system?
It’s continually destroyed and reformed to govern photoreceptor sensitivity.
What visual feature does the center-surround arrangement help detect effectively?
Contrast
What visual process is aided by the slight disparity between the left and right eye images?
Depth perception
What does the centre-surround arrangement in receptor cells primarily aid in detecting?
Contrast differences
Which structure within the brain maintains a retinotopic map well into the primary visual cortex?
Lateral Geniculate Nucleus (LGN)
What is the role of the Mach band illusion in visual processing?
To support the center-surround inhibition model
What triggers a voltage change across the cell membrane in photoreceptors?
Pigment breakdown into components
In which part of the brain are disparities between left and right eye images analyzed to provide depth clues?
Lateral Geniculate Nucleus (LGN)
What is one of the roles of separate layers within the Lateral Geniculate Nucleus?
Receiving input from cones vs. rods
Where does the crossover of fibres from both nasal retinas occur?
Optic chiasma
What continual process involving rhodopsin affects the sensitivity of photoreceptors to light?
Continuous degradation and reformation
Study Notes
Receptor Connections to Ganglia
- Receptor cells are arranged in a centre-surround pattern, where light in the centre of the ganglion receptive field has the opposite action of light in its periphery.
- This arrangement is suitable for detecting contrast in a ganglion cell's receptive field.
- A "signal" exists only if there is an interesting feature, leading to some "illusions".
- Inhibition of one receptor's activity by its neighbours enables better detection of edges.
Optic Nerve Pathway
- Information from the left visual field from both eyes is processed in the brain's right half.
- Fibres from both nasal retinas cross over in the optic chiasma.
- A retinotopic map is maintained well into the primary visual cortex.
Lateral Geniculate Nucleus
- Acts as a relay station within the thalamus.
- Separate layers receive information from both eyes.
- Separate layers receive input from cones vs. rods, motion-sensitive cells, etc.
Binocular Vision
- The left and right eyes are set slightly apart, providing a slightly different view of the world.
- The autonomous reflex is to move the eyes to reduce differences as much as possible.
- Remaining disparities provide clues about depth, as does the amount of eye movement required.
Photochemistry
- Rods and cones absorb light due to pigment molecules with broad absorption bands in the visible spectrum.
- Upon absorbing photon energy, pigment breaks down into two components, triggering a voltage change across the cell membrane.
- Rhodopsin, a combination of vitamin A and a protein, is the pigment in rods.
- Rhodopsin is continually destroyed and reformed, with its concentration governing the overall sensitivity of photoreceptors to light.
Colour Recognition
- Pigments in rods and all 3 cone types are slightly different, resulting in different wavelength sensitivity.
- Sensitivity equals the strength of signal to ganglion cells.
- Having more than one receptor type with slightly different sensitivity curves allows for the distinction of colours by associating each with a specific set of response rates.
Receptor Connections to Ganglia
- Receptor cells are arranged in a centre-surround pattern, where light in the centre of the ganglion receptive field has the opposite action of light in its periphery.
- This arrangement is suitable for detecting contrast in a ganglion cell's receptive field.
- A "signal" exists only if there is an interesting feature, leading to some "illusions".
- Inhibition of one receptor's activity by its neighbours enables better detection of edges.
Optic Nerve Pathway
- Information from the left visual field from both eyes is processed in the brain's right half.
- Fibres from both nasal retinas cross over in the optic chiasma.
- A retinotopic map is maintained well into the primary visual cortex.
Lateral Geniculate Nucleus
- Acts as a relay station within the thalamus.
- Separate layers receive information from both eyes.
- Separate layers receive input from cones vs. rods, motion-sensitive cells, etc.
Binocular Vision
- The left and right eyes are set slightly apart, providing a slightly different view of the world.
- The autonomous reflex is to move the eyes to reduce differences as much as possible.
- Remaining disparities provide clues about depth, as does the amount of eye movement required.
Photochemistry
- Rods and cones absorb light due to pigment molecules with broad absorption bands in the visible spectrum.
- Upon absorbing photon energy, pigment breaks down into two components, triggering a voltage change across the cell membrane.
- Rhodopsin, a combination of vitamin A and a protein, is the pigment in rods.
- Rhodopsin is continually destroyed and reformed, with its concentration governing the overall sensitivity of photoreceptors to light.
Colour Recognition
- Pigments in rods and all 3 cone types are slightly different, resulting in different wavelength sensitivity.
- Sensitivity equals the strength of signal to ganglion cells.
- Having more than one receptor type with slightly different sensitivity curves allows for the distinction of colours by associating each with a specific set of response rates.
Learn about the arrangement of receptor cells in a centre-surround pattern, detecting contrast, and inhibition of receptors for better edge detection. Understand the role of optic nerve pathways in vision.
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