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Exam 1 • Monday, Tuesday, Wednesday next week • WebCT testing centre • Covers everything up to and including hearing (i.e. the previous lecture)
Exam 1
• Monday, Tuesday, Wednesday next week
• WebCT testing centre• Covers everything up to and including
hearing (i.e. the previous lecture)
Exam 1
• Karla will host a review session – PE250– 3:00 to 4:00 Friday February 4– Bring specific questions to ask
A quick peek at all the other sensory systems we don’t
have time to considerTouch, Taste, Smell,
Proprioception, Thermoception and Balance
How do we Stay Balanced?
The Vestibular System
Vestibular System (Balance)
Vestibular System (Balance)
Vestibular System (Balance)
Vestibular System (Balance)
Head accelerates this way
Cupula getspushed
Fluid goes this way
Vestibular System (Balance)
Head accelerates this way
Cupula getspushed
Fluid goes this way
Vestibular System (Balance)
• movement of the cupula is detected by hair cells
• hair cells in the vestibular system are more sensitive than hair cells on the basilar membrane!
Vestibular, Visual, and Proprioceptive Systems Work Together
• Balance is a multimodal sense and is an example of cross-modal integration
• Try standing on one foot with your eyes closed!
Fun Facts about The Vestibular System
• Seasickness arises when the vestibular system and the visual system send conflicting information
Fun Facts about The Vestibular System
• Seasickness arises when the vestibular system and the visual system send conflicting information
• People can be knocked down by moving walls!
Fun Facts about The Vestibular System
• Seasickness arises when the vestibular system and the visual system send conflicting information
• People can be knocked down by moving walls!
• Alcohol causes the spins by (among other things) changing the density of the fluid in the semicircular canals
Sensory Systems:
• Touch, temperature, taste, smell
There are a variety of touch receptors
• Touch receptors send signals to the somatosensory cortex via long axons in the spinal cord
• Signals are sent to the opposite (contralateral) side of the brain
• Wilder Penfield - Montreal Neurological Institue - 1940’s
• Found somatotopic map by stimulating brain during surgery
The Homunculus
• Two classes of thermoreceptors: warm and cold
Thermoception
Taste (Gustation)
Taste buds contain
chemical receptors
Taste
What are the various “tastes”?
• Multi-dimensional scaling reveals several “varieties” of tastes:– sweet– salt– bitter– sour– umami (MSG) - possibly a protein
receptor– there may also be a lipid (fat) receptor
Taste
• Olfactory bulb receives input from olfactory receptors which contact mucus in nasal cavity
Smell
• There are thousands of different receptors for different kinds of molecules
Smell
• Olfactory receptors use a “lock-and-key” mechanism - only specific molecules will bind with a given receptor
Smell
Receptor
Odor Molecules
• Odor recognition is excellent in humans• but odor identification (naming) is very
poor• Women tend to be (slightly) better than
men at naming smells
Smell
• Smell is strongly influenced by “top-down” processes such as what you are expecting to smell
Smell
• Pheromones are not smells• Pheromones are chemical signals sent
from one animal to another
Pheromones
• Pheromones either induce a behavior in another animal or cause some physiological change
• Very common in insects...not so common in mammals...unclear role in humans
Pheromones
• For example: Androstenone, found in male pig saliva, causes a female pig to allow the male to mate with her
Fun Facts about Pheromones
• androstenone is also found in the sweat of human males!
• Does androstenone (or pheromones in general) affect humans?
• Design an (ethical) experiment…
Fun Facts about Pheromones
• Kirk-Smith & Booth (1980) sprayed some of the seats in a dentist’s waiting room with androstenone
• Compared to a control condition, more women used the androstenone seat
Fun Facts about Pheromones
• Fewer men used the androstenone seat !
Fun Facts about Pheromones
• Other possible ways in which pheromones influence humans:– synchronization of menstrual cycles– mate selection - attraction to opposite
major histocompatibility complex
Pheromones
• Pheromones do not control behavior!• Human behavior is largely under top-
down influences, but may be affected subtly by pheromones
• It is unclear whether molecules such as androstenone even qualify as pheromones - they may be just like other odour molecules
Pheromones
• “It is now possible to manufacture synthetic human pheromones and such compounds are often used in research as they are relatively easy to make, convenient to store, and easy to apply.”
Pheromones
