UCI Psychology Discussion – Description
1. Anatomy and function of the visual system.
In the correct sequence, describe the path light must take from the time it reflects off a visual stimulus, to the time it activates photoreceptors in the retina.
Explain the relationship between a photon and a photoreceptor.
Name each structure and its function.
Identify and describe the three types of cells contained in the retina.
Discuss the pattern of their interconnections, the neurotransmitter they release, and how it’s released (i.e. graded potential/action potential). In your description be sure to:
Describe the flow of information from the retina to the optic nerve. What does the optic nerve create as it exits the retina?
Name the synaptic partner of each cell (which cell-type “talks” to which cell type)?
Light moves toward the back of the retina to activate light receptors, setting off a communication chain in the opposite direction. Explain what this means.
Which type of cells does light have to travel past before it activates a third type.
Which types of cells must light pass before it gets to the type of cells it activates?
After it activates receptor cells, describe the path of communication leading to the signal leaving the retina.
Within this chain
Which cells release neurotransmitter via graded potentials?
Which cells release neurotransmitter via action potentials?
Decussation
Define decussation
Where in the visual system does it occur?
In relation to the visual field and the anatomy of the retina in each eye, how does decussation occur?
What is the result of this decussation?
2. In your own words, summarize:
What cones and rods share in common.
Their respective distribution within the retina.
Give two reasons why visual acuity is higher in the fovea.
How cones and rods release more vs. less neurotransmitter depending on the amount of light that enters the eye.
3. Compare and contrast the properties of the human photopic and scotopic visual systems.
What are convergence and divergence?
Which system is associated with convergence and which with divergence?
How are they related with color and black and white vision?
4. The striate and most of the extrastriate cortices maintain a topographic projection of the retinas. What does that mean? Relate this information to a detailed real-world example. Include: 1) the information flow from light reflecting off an object in your visual field to the information reaching the striate and extrastriate cortices; 2) how the foveal region is represented.
5. Describe the trichromatic and opponent-process hypotheses. What part of the visual system seems physiologically conducive to trichromatic processing? Which visual cortex area is strongly associated with color processing? How does Figure 3.0 demonstrate spectrally opponent cell activity?
6. Discuss the dorsal and ventral processing pathways of the visual system. Give an example of how damage to each might present in a given patient.
7. Give a real-life example of how vision would be impaired with each of the following conditions:
optic ataxia
myopia
amblyopia
macular degeneration
8. What is blind sight and what area of the visual cortex is damaged in this condition?
9. In your own words, explain Figure 7.18. How do simple cells and complex cells work together to help you perceive a bar (like in Figure 7.17) that is moving across your visual field? How does this reflect the hierarchical nature of visual analysis?
10. Explain how color blindness is related to genetics, and why it is more common in one sex over the other.
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