PSYC 4130 1st Edition Lecture 12 Outline of Last Lecture I Neuroantomy Continued a Forebrain i Pons and Medulla ii Cerebellum II Vision a Rainbow of wavelength b Photons c Photoreceptors Outline of Current Lecture III Photoreceptors A Cones B Rods IV Optic Disc V Theories of Coloring Code VI Visual Relay A Trichromatic B Opponent process C Retinex VII dLGN VIII Contraleteral Representation IX Primary Visual cortex Current Lecture Review 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 Rods These 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 disk o 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 coding o 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 off o 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 Relay o 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 dLGN o o o o o o Synapses of ganglion cell axon Preprocesses visual information First synapse outside of retina 4th step removed from actual visual experience 6 Major Cell Layers like cerebral cortex looks like an inverted U Parvocellular P Upper Four Layers cones are projecting here fine detail analysis o 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 PrimatesContraleteral Representation Primary Visual cortex o Aka Striate cortex o Midline of brain on the bank of the calcarine fissue o First cortical representation of visual signal originating in the retina
View Full Document
Unlocking...