Transcript Balance, Taste, & Smell

Other Senses: Outline
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Balance (Vestibular System)
Taste
Smell
Touch
Balance
• Three sources of balance:
– Vision
– Stretch receptors in muscles
– Vestibular system
• Worst case scenario:
– getting up in the middle of the night (no vision), from your
futon (poor info from stretch receptors), in a yacht (poor
vestibular info).
Vestibular System: Functions
• Balance
• Coordinates head
& body movements
• Keep eyes fixed
when head moves
Semicircular Canals
• Rotations (3-D)
Dizziness is triggered
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By rotation (kids)
By hot water in ear:
stimulates movement
of fluid in vestibular
chambers
vertigo
Vestibular Sacs: Function
– linear accelerations
– static head positions
From inner ear, output goes to
Medulla & from there to:
- Spinal Cord,
- Oculomotor Nerve,
- Cortex,
- Cerebellum
Taste
• Flavor is inferred from:
– Taste (5)
– Smell (500-10,000 odors), and
– Tactile information, & pain receptors (chili peppers)
• Supertasters
– Genetic differences in receptors
– Increased sensitivity to bitterness, sweet
Taste Receptors
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Papillae
Bitter
Sweet
Sour:
Saltiness: Na+ channel
Umami
– elicited by the amino
acid glutamate found in
proteins (meat, fish,
beans, ketchup)
– MSG (monosodium
glutamate)
Taste Pathway
• Orbitofrontal
cortex (S2)
• Amygdala
• Post central
gyrus and
Insula (S1)
• Thalamus
• Medulla
• Cranial
nerves
Amygdala & OFC are important for valence, reinforcement
Olfactory System
• The primary mode of communication for most animals
• Critical for survival
– eating
• toxic substances often smell/taste bad; good things smell good
– reproduction
• mating partners
• aggression in rivals
– location of predators and prey
Olfactory Anatomy
Olfactory tract
projects to
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amygdala,
hippocampus
hypothalamus
Insula
Pheromones
• Airborne molecules that affect behavior
• Especially involved in reproduction
• VNO- Vomeronasal Organ
– Physically distinct
– evolved separately
– Projects to Limbic areas
VNO
 Somatosenses
The stimuli
 The cutaneous senses respond to several different types
of stimuli: pressure, vibration, heating, cooling, and
events that cause tissue damage (and hence pain).
 Some receptors report changes in muscle length to the
brain; providing our sense of kinethesia.
 Additional receptors provide information about the
internal organs such as the linings of muscles and the
gastrointestinal system.
 Somatosenses
Anatomy of the Skin and its Receptive Organs
 Cuntaneous sense:
 One of the somatosenses; includes sensitivity to
stimuli that involve the skin.
 Kinesthesia:
 Perception of the body’s own movements.
 Organic sense:
 A sense modality that arises from receptors located
within the inner organs of the body.