(March 10, 2010) Neuroscience Essay Test 2 Chapters 6, 7, 8, 9, 10 Transduction Our perception of vision is decoded from enormous amounts of environmental information that is captured by a physical detection of photo pigments by our photoreceptors, rods and cones, located in the retina of the eye. The conversion of this physical energy detected into neural information is known as transduction. There is about 120 million rods in the human retina and only about 7 million cones. Rods are used in distinguishing between light and dark, where cones (three different types) are used to detect red, blue, and green photo pigments. Photoreceptors are naturally in a state of depolarization from cGMP (keeps Na + channels open) without stimulation. When the receptor absorbs its specific photon a cascade is initiated which closes the Na + channel and sends a signal to horizontal cells which inhibit corresponding bipolar cells nearby and fades with increased distance from the excited photo receptor. There are three
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