1. Anthony J Greene1 Olefaction

2. Anthony J Greene2 Smell Chemical detection without the danger of ingesting poison Object identification Sexual signaling

3. Anthony J Greene3 Nasal Anatomy

4. Anthony J Greene4 Nasal Anatomy Nasal cavity - Hollow portion of head behind nose - warms air, filters out dust, houses the sense of smell Olfactory epithelium - Area of nasal cavity with olfactory receptors

5. Anthony J Greene5 Nasal Anatomy Receptors are genuine neurons (unlike photoreceptors and hair cells) Unlike other neurons, receptors are continually regenerated 1,000 different receptor types - about 1% of your DNA codes for olfactory receptors making it the largest single gene family

6. Anthony J Greene6 Olfactory Epithelium Receptors have four parts cilia, olfactory knob, olfactory rod and the axon Olfactory nerve - the axons of the olfactory receptors form bands which travel to the olfactory bulb

7. 7 Olfactory Bulb Olfactory bulb - organ which houses all the nerves which receive inputs from the olfactory receptors (mitral cells and periglomerular cells) Limbic and Thalamic connections Olfactory cortex (frontal lobe)

8. Anthony J Greene8 Early Olfactory Pathway

9. Anthony J Greene9 Central Olfactory Pathways

10. Anthony J Greene10 Central Olfactory Pathways

11. Anthony J Greene11 Central Olefactory Pathways

12. Anthony J Greene12 Central Olefactory Pathways

13. Anthony J Greene13 Central Olefactory Pathways

14. Anthony J Greene14 Central Olefactory Pathways

15. Anthony J Greene15 Perception of Smell The dimensions of smell

16. Anthony J Greene16 Perception of Smell (cont.) We can distinguish between about 10,000 different smells Different threshold levels for different smells Two thresholds for each smell -low threshold for the existence of a chemical, somewhat higher threshold to discriminate one smell from another

17. Anthony J Greene17 Perception of Smell (cont.) Adaptation - Olfactory fatigue - cross-adaptation Smell Constancy - receptors are more stimulated during a deep sniff than a shallow one - the judgment of odor intensity does not change -

18. Anthony J Greene18 Perception of Smell (cont.)

19. 19 Pheromones: Mammals Powerful effects on behavior, specifically sexual behavior, territorial behavior and identification of kin Mammals Most mammals only become sexually aroused in the presence of pheromones Increased likelihood of pregnancy Synchronization of estrus cycles Mutual recognition of mother and offspring Territory marking (e.g. dogs)

20. Anthony J Greene20 Pheromones: Mammals Releasers - trigger a specific behavioral response Primers - trigger a hormone response which increases the likelihood of certain types of behaviors

21. 21 Pheromones: Humans Humans infants can correctly identify their own mother's milk and are much more likely to nurse when its their own mother female menstrual cycles can be altered by pheromones - the sorority effect male and female behavior is highly influenced by pheromones t-shirt experiment - musky versus sweet - the musky odor is rated by males and females as unpleasant and is thought to serve as a territorial marker among males

22. Anthony J Greene22 Pheromones: Alpha Androstenol alpha androstenol (predominantly secreted by females) 1.Increase sexual arousal in males 2.Increases male perception of female attractiveness women in photographs were rated as significantly more sexually attractive when judges were first exposed to alpha androstenol 3.Increases willingness of females to initiate social contact with males females exposed to alpha androstenol were much more receptive to male-initiated contact more likely to seek out male company less likely to seek female company