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Sensation & Perception (II) 3270 Lecture 7 smell

Sensation & Perception (II) 3270 Lecture 7 smell. KEYWORDS ---- TASTE I. Taste Primaries: sweet, sour, salty, bitter,

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Sensation & Perception (II) 3270 Lecture 7 smell

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  1. Sensation & Perception (II) 3270 Lecture 7 smell

  2. KEYWORDS ---- TASTE I Taste Primaries: sweet, sour, salty, bitter, papilla (nipple) types: fungiform (fungus-like), foliate (leaf-like), circumvallate (around the ramparts), taste buds (found on papilla), respond to more than one ‘primary' taste cells (found within taste buds), no axons, connect/synapse with afferent fibres coding of quality, activity across a population, pattern of firing of nerves related to perceptual abilities in rats (responses to different salts, ammonium, potassium and sodium chloride), most fibres respond to more than one primary

  3. KEYWORDS ---- TASTE II taste thresholds depend on: temperature (different primaries alter differently), tongue region, genetics (phenylthiocarbamide: to 2/3rds of white western folk tastes bitter; 1/3rd no taste), concentration (eg. saccharin low sweet; high bitter), age, adaptation,

  4. KEYWORDS ---- TASTE III taste preferences, Humans: sweet (+); bitter (-), mostly in place at birth; Cats and chickens: indifferent to sweet; rat/cat/rabbit/sheep: salt (+); hamster: salt (-) taste cravings, salt, calcium, potassium, etc.. specific changes in threshold when deprived (eg. for salt) cultural influences, conditioned taste aversion neural pathway, uncrossed, taste cells, VII cranial nerves (corda tympani division of facial nerve), IX cranial nerve (glossopharyngeal), solitary nucleus, ventral posterior medial nucleus of thalamus,taste cortex (near mouth representation of somatosensory cortex), brain stem vomit centres

  5. The 12 Cranial Nerves 1 olfactory 2 optic 3 oculomotor 4 trochlear 5 trigeminal 6 abducens 7 facial 8 auditory and vestibular 9 glossopharyngeal 10 vagus 11 accessory 12 hypoglossal

  6. Sensory Processes 3270 Chemical senses SMELL

  7. FUNCTIONS of SMELL • Gatekeepers (good in, bad reject) • orient in space • mark territory • guide to find other animals • guide to find food • sex • humans, perfumes indicate still important • detect spoiled food • fire • anosmia • sex?

  8. DigiScents is developing this device, dubbed the iSmell, to puff appropriate smells at you as you surf the Web. Image courtesy of Digiscents, Inc.

  9. Bloodhounds can pick up a 24hr old trail. Dogs have 1,000,000,000,000 olfactory receptors and we have about 10,000,000. We can smell happiness and fear. Everyone has an unique smell .. except identical twins! Sniffer rats have been used to detect explosives!!!

  10. An olfactometer

  11. Discrimination threshold • Weber Fractions • Taste 0.08 8% • Brightness 0.08 8% • Loudness 0.05 5% • Vibration 0.04 4% • Line length 0.03 3% • Heaviness 0.02 2% • Electric shock 0.01 1% For smell, can be as low as 5% (for n-butyl alcohol)..

  12. Episodic odours 100% N of recall Lab vision Lab odours 60% 1 yr time RECALL OF ODOURS

  13. HUMAN OLFACTORY ABILITIES undershirts -- 75% identify themselves -- 75% identify gender infants can identify mothers from milk smell McClintock effect (synchonized menstrual cycles) -- works through sweat

  14. THREE PARTS TO SMELL SYSTEM 1 --- OLFACTORY 2 --- VOMERONASAL 3 --- SOMATOSENSORY --- trigeminal --- CHEMESTHESIS --- texture, heat, irritation

  15. OLFACTORY BULB

  16. The olfactory mucosa

  17. OLFACTORY EPITHELIUM

  18. Olfactory receptor neurones ---replaced every 60 days --- about 10,000,000 (in humans) --- about 1,000 types olfactory receptors (on the olfactory receptor neurones) --- about 1,000 types olfactory binding proteins --- delivers odorants to receptor neurones.

  19. Figure 15.5 (a) A portion of the olfactory mucosa. The mucosa contains 350 types of ORNs and about 10,000 of each type. The red circles represent 10,000 of one type of ORN, and the blue circles, 10,000 of another type. (b) All ORNs of a particular type send their signals to one or two glomeruli in the olfactory bulb.

  20. CONVERGENCE

  21. The olfactory receptor protein is a ‘G’ protein. It crosses the membrane 7 time. Similar to the VISUAL PIGMENT. There are about 1000 variations.

  22. A bishop’s mitre

  23. Olfactory receptor Neurones Mitral cells Granule cells

  24. ZONES of the OLFACTORY MACULA & glomerulus

  25. GLOMERULI -- balls of tangled connections between MITRAL cells and OLFACTORY RECEPTOR NEURONES. -- four zones (from macula) -- convergence (about 1,000 to 1) -- olfactory receptor types kept organized -- properties sharpened by lateral inhibition -- send information to ANCIENT paleocortex

  26. Figure 15.9 (a) The underside of the brain, showing the neural pathways for olfaction. On the left side, the temporal lobe has been deflected to expose the olfactory cortex. (Adapted from Frank & Rabin, 1989).

  27. conscious discrimination emotional response mitral cells in the olfactory bulb piriform cortex amygdala olfactory receptor neurones thalamus orbitofrontal cortex

  28. emotional response conscious discrimination Figure 15.10 Flow diagram of the pathways for olfaction. (From Wilson and Stevenson, 2006) thalamus

  29. Coding

  30. putrid fragrant ethanol burned resinous spicy HENNING SMELL PRISM

  31. Figure 15.2 (a) Two molecules that have the same structures, but one smells like musk and the other is odorless. (b) Two molecules with different structures but similar odors.

  32. Figure 15.6 Recognition profiles for some odorants. Large dots indicate that the odorant causes a high firing rate for the receptor listed along the top; a small dot indicates a lower firing rate for the receptor. The structures of the compounds are shown on the right. (Adapted from Malnic et al., 1999.)

  33. chemicals Codes in olfactory receptors fibres across-fibre pattern coding

  34. This sort of coding means you can distinguish many smells at once

  35. ZONES of the OLFACTORY MACULA & glomerulus

  36. GLOMERULAR LAYER OF OLFACTORY BULB (hot spots)

  37. Two similar compounds. Radioactive deoxyglucose. … so there is an element of mapping there too

  38. Olfactory receptor Neurones Mitral cells Granule cells

  39. MULTIMODAL INFLUENCES

  40. smell and taste

  41. Multi-modal convergence in the ORBITOFRONTAL CORTEX

  42. Neurone 1 Neurone 2 Orbito-frontal cortex: bimodal cells

  43. cognitive factors: same chemical, different responses

  44. PHEROMONES & the VOMERONASAL system

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