Chap 15 Chemical senses

Here comes your footer  Page 2 日常觀察  為何狗的嗅覺這麼好？  為何冰的東西比較沒味道？  吃和聞的味道如何 combine? Flavor = smell + taste  Chemical senses are  守門員 - 動用情緒，回憶 - 阻止不好的食物進入體內，或者遠離不好的環境 一些問題

Here comes your footer  Page 3 嗅覺（ Olfactory system ）  生存  溝通  Menstrual synchrony  Pheromones  味道  Anosmia   Detection threshold  Yes/no procedure -trials with odors along with “blank” trials -This can result in bias  Forced-choice -one with odorant and one without -Participant indicates which smells strongest 功能 偵測

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Here comes your footer  Page 5 嗅覺（ Olfactory system ）  Difference threshold  氣流影響濃度  Ofactometer  Recognition threshold  knowing names helps recognition  氣味難以用語言形容 偵測

Neural codes for olfactory quality  Olfactory mucosa is located at the top of the nasal cavity. -Odorants come in contact with the olfactory receptor neurons (ORN). Page 6

Neural codes for olfactory quality  嗅神經 (olfactory receptor neurons, ORN) -Contains olfactory receptors -350 receptors (note: only 4 visual pigments) -But, only one olfactory receptor for one ORN Page 7

Neural codes for olfactory quality  嗅神經 (olfactory receptor neurons, ORN) -Recognition profile ( 類似三元色論中三種受 器的激發組型的解釋） Page 8

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Neural codes for olfactory quality  Olfactory bulb -ORNs of a particular type send their signals to one or two glomeruli -How do the glomeruli respond to different odorants? -Optical imaging Page 10

Neural codes for olfactory quality  Olfactory bulb -Uchida 等人 (2000) 老鼠研究發現 - 碳鏈結愈長，激發的區域愈偏左 Page 11

Neural codes for olfactory quality  Olfactory bulb - 嗅球反應是取決於分子與結構的特性 - hardwired response? e.g. cat odor Page 12

Higher Level Olfactory Processing  Signals from the olfactory bulb are sent to -primary olfactory (piriform) cortex in the temporal lobe and amygdala. -Amygdala plays a role in emotional reactions to odors. -(then to) secondary olfactory (orbitofrontal) cortex in the frontal lobe.

Here comes your footer  Page 14 Higher order olfactory processing

Here comes your footer  Page 15 Higher order olfactory processing  我們通常都同時聞到並可以分 辨兩種以上的氣味  過去經驗影響嗅覺  e.g. 白酒 (Morrot et al., 2001)

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Here comes your footer  Page 18 Higher order olfactory processing de Araujo et al. People were exposed to a mixture of a sweat-like smell and a cheddar cheese flavoring. On some trials, they saw the label “cheddar cheese,” and on others, the label “body odor.” Pleasantness ratings were higher for the cheddar cheese trials. fMRI scans showed activity in the orbitofrontal cortex to be associated with the pleasantness ratings.