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Other Senses: Outline
• 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).
• Balance• Coordinates head
& body movements• Keep eyes fixed
when head moves
Semicircular Canals• Rotations (3-D)
Dizziness is triggered- By rotation (kids) - By hot water in ear:
stimulates movement of fluid in vestibular chambers
- vertigo
Vestibular System: Functions
Vestibular Sacs: Function– linear accelerations– static head positions
From inner ear, output goes to Medulla & from there to:
- Spinal Cord,
- Oculomotor Nerve,
- Cortex,
- Cerebellum
• 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
Taste Receptors
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– 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
SomatosensesThe 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.
SomatosensesAnatomy 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.
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