Review #2 - Lecture#4 Tuesday Feature analysis-eyes are...

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Lecture #4 Tuesday, January 15, 2008 Feature analysis—eyes are presented with a mass of information o You deal with by breaking up mass of information into elementary visual features What vs. where—brain treats very differently o Distinguishes so early that your eye plays a role Retina—cells lining the eye o 6 million cones, 120 million rods, 10 million bipolar cells, 1 million ganglion cells o Photoreceptors Rods—black and white; high sensitivity; low acuity (not concerned with detail); periphery; helps with night vision Cones—color, low sensitivity; high acuity; fovea o Ganglion cells—distingushes what vs. where; carry neural signals from eye to brain It is a basic neuron Action potential—what happens when a neuron fires (stimulates the neuron next to it) Causes release of neurotransmitter All or none—either fires or doesn’t; no levels; don’t change in size Firing Rate—number of fires per unit of time Excitation—stimulates neuron to cause increase in firing rate Inhibition—slows down firing rate Determination of receptive field o Record signal from particular neuron o Firing rate increasing in receptive field of neuron Ganglion Cells o Center surround receptive field—2 separate areas Allows us to break images into a series of dark and light dots o Send information to lateral geniculate nucleus o M-cells—concerned with where; associated with magnocellular Transient response (respond quickly and then turn off); large
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Review #2 - Lecture#4 Tuesday Feature analysis-eyes are...

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