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An example of my lecture slides for Sensation and Perception.
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VISION:LIGHT & THE EYE
Preparation before attending class:Read: http://www.amazon.com/Foundations-Sensation-Perception-Second-Edition/dp/1841696994, pages 159-183
Watch:http://www.youtube.com/watch?v=Lg73u1B61rMhttp://ed.ted.com/lessons/how-do-we-see-color-colm-kelleher
Check out:http://serendip.brynmawr.edu/bb/blindspot1.html
VISION:LIGHT & THE EYE
(I play “Long As I Can See The Light” by Creedence Clearwater Revival as students enter to set the mood)
Agenda
Review Neuroscience 101 lecture
Light
The Eye
REVIEW!(This is done via the clicker system, http://clickers.umd.edu/)
The _______ lobe is circled.A. occipitalB. parietalC. temporalD. frontal
The circled part(s) is(are):A. SomaB. DendritesC. AxonD. Axon terminals
The human brain has ______ connections than cells:
A. 2x moreB. 10x moreC. 100x more D. 1000x more
LIGHT
WHAT IS LIGHT?
A BRIEF HISTORY OF LIGHT
Newton
Huygens
Young
Maxwell
Planck
Einstein
3 Theories of Light
Rays
Waves
Particles
Rays
Light travels in straight lines at high speed
Useful to understand lens & images
Waves
Light is a wave vibrating at a specific frequency
Useful in understanding color perception
Particles
Light is discrete packets of energy (photons)
Useful low light levels because they can be counted individually
The visible spectrum is a limited (small) part of electromagnetic radiation
InfraredUltraviolet
Important Properties of Light
Reflection
Light rays are scattered backward
at surface
Why is this important for vision?This is how we see objects.
Transmission
Light quanta of certain wavelengths are scattered by the
molecules they hit
Why is this important for vision?This is how our eyes focus.
Absorption
Light quanta are taken up by a substance
converted to other types of energy
Why is this important for vision?This is how we convert light into neural signals
What is luminance?
A photometric measure of the energy
Measured in candelas per square meter of surface
Luminance
Summary
Physics of light
Important properties of light
Luminance
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THE EYE
Overview
Structure
Optical properties
Overview of the Eye
The Eye
The Cornea
The transparent membrane which allows light to enter and starts the process of focusing
The Iris
Responsible for controlling the diameter of the pupils and thus the amount of light reaching the retina
The Pupil
The circular aperture through which light passes. Dilates and contracts to vary light levels in the eye.
The Lens
Transparent, biconvex structure which helps the focusing process
The Retina
A light-sensitive tissue lining the inner surface of the eyeTranduces light energy into neural signals
The Fovea
The center of region of the retina
Image Size on the Retina
Focusing Images on the Retina
80% Cornea, fixed
20% Lens, variable
Accommodation
The process by which the lens adjusts shape to focus light from objects on the retina.
AccommodationIn a relaxed eye, parallel
rays from a distant object fall into focus on the retina.
Diverging rays from a nearer object will fall into focus behind the retina.
In this case, muscles in the eye change the shape of the lens to maintain focus on the retina.
(I play a part of video which reinforces how the structure of the eye supports the function of the eye)
Why do the eyes move?
Lots of reasons ...
Spatial resolution
Binocular registration
Spatial Resolution
Eye movements maintain the center of attention on the most acute part of the eye, the fovea.
Binocular Registration
Since the eyes are a short distance apart in the head, they have to make vergence movements to maintain binocular fixation
Useful in depth perception
Summary
The structure of the eye supports the function of the eye.
Eye movements serve to maintain high resolution and binocular fixation.
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