PSYC 4130 1st Edition Lecture 12 Outline of Last Lecture I. Neuroantomy Continued…a. Forebraini. Pons and Medullaii. CerebellumII. Vision a. Rainbow of wavelengthb. Photonsc. PhotoreceptorsOutline of Current Lecture III. PhotoreceptorsA. ConesB. RodsIV. Optic DiscV.Theories of Coloring CodeVI.Visual RelayA.Trichromatic B.Opponent processC.Retinex VII.dLGNVIII. Contraleteral RepresentationIX. Primary Visual cortexCurrent LectureReview: Fovea, output of retina through axons of ganglia cells which form optic nerves- Photoreceptors (table 6.1 in book)o Cones: Most prevalent in the central retina; found in the middle of fovea Sensitive to moderate to high levels of light Provide info about hue Provide excellent acuity (ability to see fine detail) How cones are wired neutrally, synapse with 1 bipolar cell, specific relay, breaks down picture o RodsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. Most prevalent in the peripheral retina; not found in the fovea Sensitive to low levels of light, activation threshold is low Provide on monochromatic info Provide poor acuity, not for fine detail; motion detection Bimodal Cant code color info - Optic disko Convergence point of ganglion cell output to brain Photoreceptor layer, bipolar layer, ganglion cells layer (Ganglion cells form the optic nerve)o Blindspot We don’t notice them, brain fills stuff in Visual field of 1 eye, compensates for other Has to do with ganglion cells coming together and where the exit - Theories of color codingo Trichromatic 3 colors- physiology of the cones Superseers* extra credit on test (4 different types of cones, see more subtle distinctions) Important is photo-pigments (photopsins), most of us have 3 of them, each cone expresses 1 and ONLY 1 420 short, 534 medium, 564 long (wavelength)o Opponent Process Based on the physiology of the ganglion cells Figure 6.18 in books One color excites them, then the other sets it offo Retinex Example: fruit in bowl- same stimulus under different light conditions Cortex is modifying the bottom up signals based upon context and experience Retinex theory is based on “top down” alteration of perception based upon context and experience- Visual Relayo Conscious: Retino-geniculate-striate Goes to thalamas (relay center/router)o Other: To Superior Colliculus: “Blindsight” To Pineal Gland: Melatonin (regulates release of melatonin) To SCN of Hypothalamus: Zeitgebers - Time keeper of the brain- dLGNo Synapses of ganglion cell axono Preprocesses visual informationo First synapse outside of retina o 4th step removed from actual visual experience o 6 Major Cell Layers (like cerebral cortex) [looks like an inverted U]o Parvocellular (P): Upper Four Layers- cones are projecting here, fine detail analysiso Magnocellular (M): Lower Two Layers- convergence of lots of rods, feeds into more ventral layers of dLGN, brings info in about big stuff (large objects moving; location in periphery)o Also “Koniocellular” in Primates- - Contraleteral Representation- Primary Visual cortexo Aka “Striate cortex”o Midline of brain, on the bank of the calcarine fissueo First cortical representation of visual signal originating in the
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