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Lecture 6

BIOL 520 Lecture Notes - Lecture 6: Lateral Geniculate Nucleus, Superior Colliculus, Relative Direction

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BIOL 520

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Psych 470 Lecture 6 Chapter 6 Vision
The Stimulus:
o Sensory Receptors: specialized neurons that detect a particular category of
physical events.
o Sensory Transduction: The process by which sensory stimuli are transduced into
slow, graded receptor potentials.
o Receptor Potential: A slow, graded electrical potential produced by a receptor
cell in response to a physical stimulus.
Basically, we need light in order to see, but the brain needs to take light
information and turn it in to a neural signal (sensory transduction).
Humans can only see within the electromagnetic spectrum (from 400-700 nm).
Dimensions of Color Perception:
o Saturation: purity (strength of color)
o Brightness: lightness level
Eye movements:
o Vergence Movement: Slow eye movements adjustig to ioig isual
aspects, short range movement where muscles curve in or out depending on
visual stimulus.
o Saccadic Movement: Short, fast bursts of movement when looking around
(reading, looking at hidden pictures). Not controllable.
o Pursuit Movement: Slow movements that you can control (following an object
with your eyes).
Eye structure:
o Cornea: outer layer of protection
o Iris: colored portion of eye
o Pupil: lets light into eye and contracts and dilates with different amounts of light.
Darkness = dilated iris
o Lens: focuses light on the back of the eye (on the retina), is malleable
(accommodates light to focus it in a particular position)
o Ciliary muscles: muscles that move the lens.
o Retia: hat akes you see, has photoreeptors, ipolar ells, and ganglion
cells (3 layers).
Axons of ganglion nerves are what goes to the brain to give information
to the brain.
Light goes from ganglion cells to bipolar cells to photoreceptors.
o Fovea: Region of the retina that mediates the most acute vision of birds and
higher mammals.
Give you very high acuity (sharpness) vision (center of vision).
Color-sensitive cones are the only type of photoreceptor found here.
Photoreceptors break up light.
o Optic Disk: location of exit point from retina of fibers of ganglion cells that form
the optic nerve.
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