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Psychology 304:
Brain and Behaviour
Lecture 31
1
With respect to Chapter 10, you are only responsible for the readings noted
in the syllabus. The excluded section headings are:
1. Different mechanisms enable the eyes to work over a wide range of light
intensities (p. 289-290).
2. Photoreceptors excite some retinal neurons and inhibit others (p.
295-296).
3. Neurons in the retina and the LGN have concentric receptive fields (p.
296-298).
4. Neurons in the visual cortex have varied and complicated receptive
fields (p. 298-299).
5. Most cells in the primary visual cortex are tuned to particular spatial
frequencies (p. 299-301).
6. Color is created by the visual system (p. 306).
7. Color perception requires receptor cells that differ in their sensitivities to
different wavelengths (p. 306-308).
8. Some retinal ganglion cells and parvocellular LGN cells show spectral
opponency (p. 308-309).
9. Some visual cortical cells and regions appear to be specialized for color
perception (p. 309-310).
10. Most mammalian species have some color vision (p. 310).
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The Chemical Senses and Visual System
1. What are the biological mechanisms associated with
smell?
2. What is the structure of the eye and where are the
receptors for light?
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By the end of today’s class, you should be able to:
1. describe the structural and functional features of the
receptor organs of the olfactory system.
2. review the pathway by which olfactory information is
transmitted from receptors to the brain.
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3. identify the locations and functions of the primary
cortex and secondary cortex for the olfactory system.
4. describe the structural and functional features of the
eye ball and retina.
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What are the biological mechanisms associated with
smell?
• The function of smell (i.e., the olfaction system) is to
monitor the chemical content of the environment. The
olfactory system detects airborne chemicals that are
drawn over receptors in the nasal passage.
• The receptors for smell are found in the upper part of the
nose, embedded in a layer of tissue called the olfactory
epithelium.
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Olfactory Epithelium
Olfactory Receptors and Pathways
of the Olfactory System
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Secondary olfactory cortex
Pathways of the Olfactory System
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What is the structure of the eye and where are the
receptors for light?
• Light waves pass through the cornea, pupil, and lens
of the eye, ultimately falling on the retina, the interior
lining of the back of the eye.
10
Vitreous humor
The Human Eye
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• The retina is composed of five layers of different types
of neurons: receptors, horizontal cells, bipolar cells,
amacrine cells, and retinal ganglion cells.
• Light reaches the receptor layer only after passing
through the other four layers; for this reason, the
cellular organization of the retina is described as
“inside-out.”
• The point at which the optic nerve exits the eye is
referred to as the optic disc and produces a “blind
spot” in the visual field.
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The Cellular Structure of the Retina
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The Chemical Senses and the Visual System
1. What are the biological mechanisms associated with
smell?
2. What is the structure of the eye and where are the
receptors for light?
14