GSU NEUR 3000 - NEUR 3000 - Chapter 9 (30 pages)

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NEUR 3000 - Chapter 9



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NEUR 3000 - Chapter 9

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Pages:
30
School:
Georgia State University
Course:
Neur 3000 - Hon Principles of Neuroscience

Unformatted text preview:

THE EYE NEUR 3000 Dr Joseph J Normandin THE EYE IS THE BEGINNING OF THE VISUAL SYSTEM The eye allows us to focus electromagnetic energy and transduce this into an electrical signal Humans can see a small portion of the entire spectrum of electromagnetic energy The visual spectrum GROSS ANATOMY OF THE EYE GROSS ANATOMY OF THE EYE GROSS ANATOMY OF THE EYE IMAGE FORMATION IMAGE FORMATION The lens helps to focus light through a process called accommodation The pupil assists in image formation be limiting or enhancing the amount of light entering the eye as well as adjusting depth of focus IMAGE FORMATION We can only see what is in front of us and what light our eyes can collect The extent of our environment that we can see is the visual field Each eye has its own visual field a part of which overlaps with the other The ability of the eye to distinguish two points is called visual acuity Dependent on the density of visual receptor cells photoreceptors on the retina ANATOMY OF THE RETINA Photoreceptors on the retina transduce light into neural activity Photoreceptors synapse with bipolar cells which in turn synapse with ganglion cells whose axons form the optic nerve Horizontal cells and amacrine cells communicate in between the other cell types ANATOMY OF THE RETINA ANATOMY OF THE RETINA There are 125 million photoreceptors on the back of the retina Contain pigments that are sensitive to particular wavelengths of light Photoreceptors are divided into two general types Cone photoreceptors cones Require substantial stimulation Bright light vision 3 types of pigments Color Rod photoreceptors rods 100x more sensitive than cones Low light vision 1 type of pigment No color or one ANATOMY OF THE RETINA Distribution of rods and cones on the retina is non homogenous Peripheral vision has high sensitivity for low light Central vision has high acuity in bright light PHOTOTRANSDUCTION Phototransduction in rods When not transducing light there is a dark current in photoreceptors



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