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50 Cards in this Set

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