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How do we Stay Balanced?. The Vestibular System. Vestibular System (Balance). Vestibular System (Balance). Vestibular System (Balance). Vestibular System (Balance). Head accelerates this way. Fluid goes this way. Cupula gets pushed. Vestibular System (Balance). Fluid goes this way.
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How do we Stay Balanced? The Vestibular System
Vestibular System (Balance) Head accelerates this way Fluid goes this way Cupula gets pushed
Vestibular System (Balance) Fluid goes this way Head accelerates this way Cupula gets pushed
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 • 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
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
The Homunculus • Wilder Penfield - Montreal Neurological Institue - 1940’s • Found somatotopic map by stimulating brain during surgery
Thermoception • Two classes of thermoreceptors: warm and cold
Taste (Gustation) Taste buds contain chemical receptors
Taste What are the various “tastes”?
Taste • 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
Smell • 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 Odor Molecules Receptor
Smell • 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
Pheromones • 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
Fun Facts about 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 !
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