Study Questions exam 2. 2008

Study Questions exam 2. 2008 - Study Questions Exam 2...

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Study Questions Exam 2 Sensory Systems: 1.  Using several visual or auditory illusions, explain the difference between sensation and perception. Sensation occurs when the receptors for sensory systems register energy from the external environment. Blobs, lines. Perception is when information from sensation is processed within the CNS. Words within blobs. One line longer than the other. 2. What is synesthesia and what are the possible explanations (neural) for this phenomenon? Synesthesia is when you have cross-modal sensations, like touch causes taste, or you can taste shapes. This could be caused by crossing of labeled lines, disorder of development (babies experience it and differentiation causes labeled lines), learned-association (you condition smells to be sweet by pairing with sugar water), or, as Richard Cytowic says, it is an evolutionary advantageous adaptation. 3. What model or theory of visual perception is associated with Hubel and Wiesel? What contribution won them  the Nobel? That visual inputs are hierarchical – lower levels of the pathway, neurons only respond to the fundamental properties of objects (spots of light), then lines, then moving lines etc 4. What is lateral inhibition and how does it occur? When an excited neuron can reduce the activity of its neighbors, it increases the contrast and sharpness in visual response. Rodsfrom the center of the stimulus transduce the light signal to the brain, but different rods on the outside of the stimulus send a dark signal to the brain. This contrast creates a sharper image. 5. What is the law of specific nerve energies and why is it important? The nature of perception is defined by the pathway over which sensory information is carried. So visual inputs lead to vision. 6. How is location of an object in the visual field coded for by the visual cortex? Light goes through lens, projected on retina where it stimulates photoreceptors which at rest inhibit bipolar cells. Light stimulation close sodium channels, which leads to hyperpolarizing generator potentials. Inhibition is inhibited and bipolar cells are depolarized, leading to action potentials in ganglion cells. These leave retina, cross over at optic chiasm, and synapse in the LGN of the thalamus. These cells send long axons to the primary visual cortex – striate cortex and area V1, then project to secondary visual cortex 7. How is location of a noisy object in the visual field coded for by the auditory cortex? Location coding occurs by comparing arrival time of sounds from left and right ears 8. What’s the difference between rods and cones in what they are good for in terms of visual processing. Where are  they? What kinds of info do they process and how are they different? Rods are in the periphery, best for dim lights and shape/movement. They see black and white. Cones are not as 
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This note was uploaded on 04/21/2008 for the course PSY 91 taught by Professor Williams during the Spring '08 term at Duke.

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Study Questions exam 2. 2008 - Study Questions Exam 2...

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