1. How does our brain determine the direction of a sound?

1. 1. How does our brain determine the direction of a sound? • By calculating the slight difference in time that it takes sound waves to reach the two ears • Also by the difference in intensity

2. 2. To what does “pitch” refer? • The subjective experience of a sound being high or low

3. 3. For which type of sounds does frequency theory apply? 4. For place theory? • Frequency theory – applies to low pitched sounds • Place theory – determines medium to higher-pitched sounds

4. 5. What is the difference between the two theories’ explanations? • Frequency theory explains that the rate at which nerve impulses reach the brain determines how low the pitch of sound is • Place theory explains that higher pitched sounds are interpreted based upon the location on the basilar membrane (in the cochlea) where maximum vibration occurs

7. Fig. 8-20. Severe noise damage. Shown is a total loss of a region of the organ of Corti along with the nerve fibers that innervated it. MNF=myelinated nerve fibers; OC=organ of Corti. (Photo and editorial help courtesy of Barbara A. Bohne and Gary W. Harding, Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO)

9. 6. What are the functions of the vestibular system? • Sensing the position of the head • Keeping the head upright • Maintaining balance

10. 7. What causes motion sickness? • When there is a sensory mismatch between the information from the vestibular system and the information reported by your eyes

11. 8. What is Meniere’s disease? • Sudden attacks of dizziness, nausea, vomiting , spinning, and head-splitting buzzing sounds caused by an infection of the inner ear

15. 9. Why are taste and smell chemical senses? • Because the raw materials being sensed and processed are chemicals

16. 10. How often are taste buds replaced? • About every 10 days

17. 11. What percentage of people are supertasters? • 25%

18. 12. How do we experience flavor? • The combination of taste and smell, as well as other sensory input and our experiences

19. 13. Where in the brain are the impulses for smells processed (first)? • In the olfactory bulb

20. 14. Approximately how many different odors can humans identify? • About 10,000

21. 15. What are three different functions of olfaction? • Identify the taste of food • Warn of potentially dangerous food • To elicit strong memories associated with emotion

23. Touch • 1. includes pressure, temperature (warm and cold receptors), and pain • 2. arise from stimulation of receptors on or near the surface of the skin • a. hair receptors, free nerve endings, and Pacinian corpuscles act as receptors • b. processed in the somatosensory cortex • C. The Experience of Pain • 1. Nerve endings are the receptors for pain and send the information to the brain via the spinal cord • a. large nerve fibers carry the impulses faster than small • b. large myelinated fibers (A-delta) are responsible for sensations of sharp localized pain • c. thin unmyelinated fibers (C fibers) are responsible for longer lasting, less localized, aching or burning pain (also carries temperature information)

24. 2. Gate-control theory • hypothesized that a “gate” (a pattern of neural activity) in the spinal cord can block the pain signals from reaching the brain • helps explain why rubbing an injured spot can temporarily alleviate pain (creates a pattern of neural activity that blocks the signals from the C fibers) • not much empirical data to support the theory • 3. Attention and emotional state has a lot to do with whether you experience pain and its intensity • 4. The production of endorphins act as pain relievers • thought that acupuncture releases endorphins thereby relieving the symptoms of chronic pain • 5. Cultural differences in pain perception can be attributed to the willingness to tolerate