Transcript The Chemical Senses • Olfaction and Gustation • Research difficulties • Pheromones • Gustation (taste) – – – – – four taste qualities flavor tongue localization survival significance sensory coding Sensation and Perception - chemical_senses.ppt ©

The Chemical Senses
• Olfaction and Gustation
• Research difficulties
• Pheromones
• Gustation (taste)
–
–
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four taste qualities
flavor
tongue localization
survival significance
sensory coding
Sensation and Perception - chemical_senses.ppt
© 2001 Dr. Laura Snodgrass, Ph.D.
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The Chemical Senses
• Olfaction (smell)
– the basic smells
• Amoore
• Henning’s Odor Prism
– receptor
– coding
– survival significance
– neural pathways
Sensation and Perception - chemical_senses.ppt
© 2001 Dr. Laura Snodgrass, Ph.D.
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The Chemical Senses
• Olfaction and Gustation
– sensory systems for the detection of chemicals
– olfaction (smell) detects chemicals in the air
– gustation detects chemicals dissolved in a solution
• saliva helps to dissolve the chemical
• Research difficulties
– hard to control amount of odorant reaching the smell receptors
– very rapid adaptation
– taste buds die off every 4 - 11 days
Sensation and Perception - chemical_senses.ppt
© 2001 Dr. Laura Snodgrass, Ph.D.
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Pheromones
• Animal studies
– chemical communication by both taste and smell
• Human studies
– gender identification
• men - musky
• women sweet
– babies can identify own mother’s milk by smell
– family members can identify family t-shirts
– Vomeronasal system
• role of smell is sexual attraction - the perfume industry
– moose musk, and “pheromone” the perfume
• the McClintock effect
Sensation and Perception - chemical_senses.ppt
© 2001 Dr. Laura Snodgrass, Ph.D.
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Gustation
• Four basic taste qualities
– sweet, sour, bitter, salt
• Flavor
– not the same as taste
• an apple, onion, and potato all have the same taste, they differ in flavor
– flavor is composed of: taste, smell, touch (texture), temperature, color, and
sometimes pain
– learned preferences for flavors
Sensation and Perception - chemical_senses.ppt
© 2001 Dr. Laura Snodgrass, Ph.D.
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Tongue Localization
The entire surface can detect all tastes.
However, the tip is most sensitive to
sweet, the sides to salt and sour, the
back of the tongue and the soft palate
respond most strongly to bitter.
Sensation and Perception - chemical_senses.ppt
© 2001 Dr. Laura Snodgrass, Ph.D.
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Survival Significance of Taste
Taste
Stimulus
Significance
Sweet
Complex organic
molecules
energy
(sugars and carbohydrates)
Salt
NACL
Nerve conduction
Sour
Acids (H+)
Spoiled food
or vitamins
Bitter
Organic alkaloids
Metallic salts
poison
Sensation and Perception - chemical_senses.ppt
© 2001 Dr. Laura Snodgrass, Ph.D.
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Sensory Coding
• Across fiber pattern coding
– the pattern of activity across many
receptors codes for the taste
– the same receptors may respond but
with different relative amounts of
activity
– the graph shows four sample taste
buds and how they might respond to
each taste
• Specific tastes are identified in
the frontal lobe
90
80
70
60
sweet
sour
salt
bitter
50
40
30
20
10
0
A
Sensation and Perception - chemical_senses.ppt
B
© 2001 Dr. Laura Snodgrass, Ph.D.
C
D
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Olfaction
• Basic smells
– Amoore’s seven basic smells
• camphoraceous
• pungent
• floral
• ethereal
• minty
• musky
• putrid
– all other smells would be a combination of these
– later Amoore had 14 basics, then 21 basics, etc..
Sensation and Perception - chemical_senses.ppt
© 2001 Dr. Laura Snodgrass, Ph.D.
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Olfaction
Henning’s Odor Prism - a graph of 6 basic
smells and their possible combinations
Sensation and Perception - chemical_senses.ppt
© 2001 Dr. Laura Snodgrass, Ph.D.
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Olfactory Receptor
Olfactory mucosa
(epithelium)
Sensation and Perception - chemical_senses.ppt
© 2001 Dr. Laura Snodgrass, Ph.D.
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Sensory Coding
• Chromatographic theory (tentative)
– spatial pattern
– pattern of activity across many receptors
– different odors cause activity in different locations on the olfactory mucosa
• No one theory has strong evidence to support it
Sensation and Perception - chemical_senses.ppt
© 2001 Dr. Laura Snodgrass, Ph.D.
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Survival Significance
• Taste acts to detect important nutrients and to warn us
about bad food or poison
• How might smell function to:
– warn us about danger?
– attract us to things that will help us survive or bring us pleasure?
Sensation and Perception - chemical_senses.ppt
© 2001 Dr. Laura Snodgrass, Ph.D.
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Neural Pathways
• The olfactory mucosa is directly linked to the olfactory
bulb which sends the information to the frontal lobe for
identification
• Collaterals (copies of the signals) are send to three
other structures
– amygdala - where emotions are processed
– hippocampus - where memories are processed
– hypothalamus - processing involved in eating, drinking, and sexual behavior
• Smell is strongly associated with emotions, memory,
eating, drinking, and sexual behavior
Sensation and Perception - chemical_senses.ppt
© 2001 Dr. Laura Snodgrass, Ph.D.
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