PSYC 380 Lecture Notes - Lecture 3: Resting Potential, Nonlinear System, Linear System
28 Feb 2017
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Separate these layers are plexiform layers containing the fibers and synapses connecting the cell layers together: far more photoreceptors (100 million+) than ganglion cells (1 million) When photoreceptors collect light, they hyperpolarize, not depolarize. Horizontal cells: accentuate response patterns towards dominant responses. Off bipolar cells keep polarity- less activity in ganglion cell and everywhere else. Amacrine cells: contribute to lateral inhibition/sensitivity, too; respond to changes in light patterns over time. Ganglion cells: 3 types: midget, parasol, bistratified: first stage of processing to yield action potential, axons form optic nerve, 1. 25 million per eye. 1 type of rod, 3 types of cones. 95% of all photoreceptors are rods; 120 million rods & 6 million rods in each retina. Outer segment of each receptor contains a stack of disks packed with light-sensitive pigment molecules. Each molecule consists of a protein (opsin) and a light-catching portion (chromophore) Pigment molecules use 11-cis retinal as chromophore (photo- isomerization of retinal:)
