Chapter Ten Homework
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Chapter Ten Homework 1. What is the source of most of the input to the left LGN? The left LGN receives retinal information about the right visual field. Left LGN neurons receive synaptic input from the retinal ganglion cells in the nasal half of the right retina and the temporal half of the left retina. In the left LGN, the left eye axons synapse on cells in layers 2, 3, and 5 and the right eye axons synapse on cells in layers 1, 4, and 6. 2. What is meant by the statement that there is a map of the visual world in the striate cortex? Each striate cortex receives input from one LGN, which means each cortex will receive input from the opposite half of the visual world. The left striate cortex will receive input from the left half of each retina, which corresponds to the right half of the world. Now each point of this left half of each retina is projected to a distinct point on the cortex. Now, adjacent locations on the retina project to adjacent points on the striate cortex. If you were to take the retina and the striate cortex and lay them out flat, the retina would be the terrain and the striate cortex would be a map of that terrain. A point-by-point relationship occurs between the retina and the striate cortex and can be considered a topographic map, therefore, the cortex is said to have a retinotopic map of the retina. 3. What is parallel processing in the visual system? Give two examples.
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Neuroscience, Exploring the Brain
Transcript of Chapter Ten Homework
Chapter Ten Homework
1. What is the source of most of the input to the left LGN?
The left LGN receives retinal information about the right visual field. Left LGN neurons receive synaptic input from the retinal ganglion cells in the nasal half of the right retina and the temporal half of the left retina. In the left LGN, the left eye axons synapse on cells in layers 2, 3, and 5 and the right eye axons synapse on cells in layers 1, 4, and 6.
2. What is meant by the statement that there is a map of the visual world in the striate cortex?
Each striate cortex receives input from one LGN, which means each cortex will receive input from the opposite half of the visual world. The left striate cortex will receive input from the left half of each retina, which corresponds to the right half of the world. Now each point of this left half of each retina is projected to a distinct point on the cortex. Now, adjacent locations on the retina project to adjacent points on the striate cortex. If you were to take the retina and the striate cortex and lay them out flat, the retina would be the terrain and the striate cortex would be a map of that terrain. A point-by-point relationship occurs between the retina and the striate cortex and can be considered a topographic map, therefore, the cortex is said to have a retinotopic map of the retina.
3. What is parallel processing in the visual system? Give two examples.
Parallel processing is the ability of the brain to process incoming stimuli simultaneously in different ways. This is extremely important in vision. Some examples include our two eyes, and on and off bipolar cells.
4. If a child is born cross-eyed and the condition is not corrected before the age of 10 years, binocular depth perception will be lost forever. This is explained by a modification in the circuitry of the visual system. From our knowledge of the central visual system, where do you think the circuitry has been modified?
The noncorresponding input from the two misaligned eyes prevents the formation of binocular neurons in the striate cortex or any extra striate visual area.
