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50 Cards in this Set
- Front
- Back
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What is light?
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waves of electromagnetic energy that are betweeen 380 and 760 nanometers in length
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Name two important properties of light
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intensity and wavelength
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wavelength is to ______as intensity is to _______
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wavelength is to color as intensity is to brightness
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Function of the Iris
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regulating the amount of light reaching the retinas
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Where does light enter the eye?
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the pupil
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What are two factors that cause the pupil size to respond to changes in illumination?
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sensitivity (ability to detect presence of dimly lit objects) and acuity (ability to see the details of objects)
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What happens when there is a ciliary muscle contraction in the lens?
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the tension is reduced
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Accommodation
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process of adjusting the configuration of the lenses to bring images into focus on the retina
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Binocular Disparity and it's importance
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Difference in the position of the same image on the two retinas-constructs 3D perception from 2D retinal images
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5 layers of retinal cells- front to back
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retinal ganglion, amacrine, bipoler, horizontal, receptors
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blind spot
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Gap in receptor layer, result of bundling of retinal ganglion cell axons leaving the eye
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fovea
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area of retina that specializes in high-acuity vision
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Photopic vision
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cone-mediated vision, good lighting, high-acuity, color
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scotopic vision
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rod-mediated vision, lacks detail and color
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duplexit theory of vision
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cones and rods mediate two different kinds of vision
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Visual Transduction
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conversion of light to neural signals by the visual receptors
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How are signals transmitted through the neural system?
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inhibition
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M channel
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magnocellular layer: neuron with a large cell body, responsive to movement, rods provide input
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P channel
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parvocellular layer: neuron with small cell body, responsive to color, fine pattern details, slowly moving objects, respond to cone input
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Rhodopsin, importance
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pigment that responds to light; is the scotopic photopigment (absorption of rhodopsin correlates with the scotopic spectral sensitivity curve)
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how do signals from eh left visual field reach the right primary visual cortex?
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temporal hemiretina of right eye, nasal hemiretina of left eye
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Neural signals are carried from retina to lateral geniculate nuclei by what axons?
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retinal ganglion cells
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Where do the retinal ganglion cells leave the eye?
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blind spot
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How do the retinal ganglion cells cross over?
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optic chiasm
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How is the retina-geniculte-striate system laid out?
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retinotopically-organized by levels
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What are the 3 levels of the retina-geniculate-striate system?
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Retinal Ganglion Cells, lateral geniculate neurons (thalamas), striate neurons of IV neurons
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Contrast Enhancement
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Firing rate of receptors on each side of an edge
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What do all 3 neurons n retina-geniculate-striate system have in common?
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circular receptive fields, monocular (receptive field in one eye) receptive fields have an excitatory area AND inhibitory area
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Flow of neurons in Primary Visual Cortex
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on center/off center cells, simple cells, complex cells
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What sid Hubel and Wiesel theory state?
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vertical columns of primary visual cortex are organized by input from eyes entering layer IV's in alternating patches. Specializes in straight lines in a particular orientation.
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What are the 3 levels of the retina-geniculate-striate system?
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Retinal Ganglion Cells, lateral geniculate neurons (thalamas), striate neurons of IV neurons
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Contrast Enhancement
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Firing rate of receptors on each side of an edge
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What do all 3 neurons n retina-geniculate-striate system have in common?
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circular receptive fields, monocular (receptive field in one eye) receptive fields have an excitatory area AND inhibitory area
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Flow of neurons in Primary Visual Cortex
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on center/off center cells, simple cells, complex cells
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What sid Hubel and Wiesel theory state?
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Receptive field causes simple or complex cells to respond in alternating patches from illuminating light, vertical columns of primary visual cortex are organized. Specializes in straight lines in a particular orientation.
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Hubel and Wiesel thought functional columns prefered what kind of lines?
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straight line, different orientation
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DeValois though the visual cortex operated on what kind of spatial frequency?
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neurons respond to frequencies and orientations of sine-wave gratings, not straight lines
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What are the achromatic and chromatic colors?
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achromatic: black,white,gray
chromatic:blue,green,yellow |
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Component Theory
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3 kinds of color receptors (trichromatic theory) any color can be made by mixing together 3 diff wavelenghts of light in diff proportions
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opponent process theory
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2 color encoders, 1 brightness encoder based on wavelength and absorbtion(complementry colors red inhibits green, yellow inhibits blue)
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microspectrophotometry
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measures absoption spectrum of photopigment contained in cone
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What is color Constancy?
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tendency for an object to stay the same color despite major change in wavelenghts of light that it reflects
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Land's retinex theory?
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color of an object is determined by it's reflectance-proportion of light of different wavelengths that surface reflects
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Simple Cells
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bars of light in particular location and orientation, monocular, don't respond to continuous stimuli
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Comlex Cells
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any location, cells in striate cortex, binocular
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Explain the Dorsal stream in high order processing
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behavioral control path, "where"
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Explain the Ventral Stream in high-order processing
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conscious perception path, "what"
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What is one thing rod and cone receptors do, and one thing they don't?
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show graded changes in membrane potential charge but do NOThave action potential
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4 steps in the retina
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1) light activates pigment
2) reduces cGMP in cytoplasm 3) closes cGMP gated ion chan (less Na+ in cell) 4) release glutamate/ or blocked |
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what is parallel processing?
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info sharing among cells
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