How do we Stay Balanced?

1. How do we Stay Balanced? The Vestibular System

2. Vestibular System (Balance)

3. Vestibular System (Balance)

4. Vestibular System (Balance)

5. Vestibular System (Balance) Head accelerates this way Fluid goes this way Cupula gets pushed

6. Vestibular System (Balance) Fluid goes this way Head accelerates this way Cupula gets pushed

7. 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!

8. Vestibular, Visual, and Proprioceptive Systems Work Together • Try standing on one foot with your eyes closed!

9. Fun Facts about The Vestibular System • Seasickness arises when the vestibular system and the visual system send conflicting information

10. 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!

11. 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

12. Sensory Systems: • Touch, temperature, taste, smell

13. There are a variety of touch receptors

14. 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

15. The Homunculus • Wilder Penfield - Montreal Neurological Institue - 1940’s • Found somatotopic map by stimulating brain during surgery

16. Thermoception • Two classes of thermoreceptors: warm and cold

17. Taste (Gustation) Taste buds contain chemical receptors

18. Taste What are the various “tastes”?

19. 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

20. Smell • Olfactory bulb receives input from olfactory receptors which contact mucus in nasal cavity

21. Smell • There are thousands of different receptors for different kinds of molecules

22. Smell • Olfactory receptors use a “lock-and-key” mechanism - only specific molecules will bind with a given receptor Odor Molecules Receptor

23. 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

24. Smell • Smell is strongly influenced by “top-down” processes such as what you are expecting to smell

25. Pheromones • Pheromones are not smells • Pheromones are chemical signals sent from one animal to another

26. 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

27. Fun Facts about Pheromones • For example: Androstenone, found in male pig saliva, causes a female pig to allow the male to mate with her

28. 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…

29. 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

30. Fun Facts about Pheromones • Fewer men used the androstenone seat !

31. Pheromones • Other possible ways in which pheromones influence humans: • synchronization of menstrual cycles • mate selection - attraction to opposite major histocompatibility complex

32. 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