PSYCH 1XX3 Lecture Notes - Visual Cortex, Lateral Geniculate Nucleus, Visual Acuity

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Psych 1XX3 Vision I & II Live Lecture
Sensation converts energy into nerve impulses.
Specialized receptors i.e. photoreceptors (rods and cones in the retina)
collect photon of light and encode that into vision.
Perception: interprets nerve impulses.
Unconscious perceptual mechanism at work
o Optical illusions
o The fact that all four in the top row interpret the same way and the
bottom is interpreted the same way is because the brain assumes
there is a single light source.
o The light source is the sun.
o The brain assumes that the light source comes from above (sun)
o Brain assumes that like objects are grouped together.
Sensation: stimuli to nerve impulse
o As photons of light enter your eye, they are focused in by the
retina and the image appears upside down
o Brain adapts to convert this to a right-side up image great adaptive
ability i.e. focus
o Visual acuity physically limited by photoreceptors. Visual acuity refers
to the ability to distinguish between 2 dots, are there two pixels or
one?
o Visual acuity eye doctor chart
o Hyperacuity judging a relative distance
o Hyperacuity is not physically limited by photoreceptors.
o Retina to the primary visual pathway.
o Travels to the lateral geniculate nucleus.
o Back to v1 of the primary visual cortex.
o As you travel along the primary visual pathway the information is
compressed.
Processing input in the primary visual cortex.
o Organized into orientation columns respond maximally to a certain
stimulus.
o Ocular dominance columns left and right eye.
o V1 organization: shaped by input?
Ferret experimentation
What if you rerouted this info? Instead of thalamus to visual
cortex. Experimenter changed the route from thalamus to
temporal lobe.
Temporal lobe organized itself as if it was the visual cortex.
Blind sight
o Man who was legally blind extensive damage to primary visual
cortex, info sent to brain, which cannot do anything with the input.
o Some visual processing intact even though there is damage to the
primary visual cortex.
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