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 consider Touch, Taste, Smell, Proprioception, Thermoception and Balance

How do we Stay Balanced? The Vestibular System

Vestibular System (Balance)

Head accelerates this way Cupula gets pushed Fluid goes this way

Vestibular System (Balance) Head accelerates this way Cupula gets pushed 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 ’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