Class # 9: Sens Mech,Smell & Taste, p. 1

SENSORY MECHANISMS General Aspects and Terminology • Some mechanisms are common elements for most types of sensation and perception. These eleements include: • The process of transduction • The process of coding • The relationship between stimulus and perception Class # 9: Sens Mech,Smell & Taste, p. 1

SENSORY MECHANISMS Transduction Class # 9: Sens Mech, Smell & Taste, p. 2

SENSORY MECHANISMS Coding Class # 9: Sens Mech, Smell & Taste,p. 3

BUT>>>>>> SENSORY MECHANISMS Coding (cont’d) Class # 9: Sens Mech, Smell & Taste,p. 4

  Are perceptions copies of physical stimuli?   SENSORY MECHANISMS The relationship between stimulus and perception Cartoons associated with the case of Mr. Amadou Diallo, an emigrant from West Africa, who, returning home after work one evening in 1999, was shot to death by undercover New York police officers when he reached into his pocket to pull out a small dark object. The police were were looking for an armed rapist. The object turned out to be Diallo’s wallet. Cartoons from the following website: cagle.slate.msn.com/news/diallo/ Class # 9: Sens Mech, Smell & Taste, p. 5

  Are perceptions copies of physical stimuli?   SENSORY MECHANISMS The relationship between stimulus and perception (cont’d) Obviously, the answer is an emphatic NO!! Perceptions are constructions by our CNS, that are influenced by the nervous system’s ability to learn and its dynamic integration, modulation, and flexible controls of stimulus information. We will discuss some of these abilities during class. Class # 9: Sens Mech, Smell & Taste, p. 6

CHEMOSENSES: SMELL (olfaction) and TASTE (gustation) Class # 9: Sens Mech,Smell & Taste, p. 7

CHEMOSENSES: Olfaction Class # 9: Sens Mech, Smell & Taste, p. 8

Receptors CHEMOSENSES: Olfaction (cont’d) • Telereceptors • Located in the nose • The transduction part of the receptor looks like a dendrite with cilia • ~60 day life cycle • more than 1,000 types Class # 9: Sens Mech, Smell & Taste, p.9

CHEMOSENSES: Olfaction (cont’d) Class # 9: Sens Mech, Smell & Taste:, p. 10

1st synapse in olfactory bulb Patterns of activation of glomeruli in the rat olfactory bulb produced by exposure of the olfactory mucosa to three different odorants. (From: Rubin BD, Katz LC Neuron 1999;23:499-511) CHEMOSENSES: Olfaction (cont’d) Routes of information transfer through the CNS and submodality coding Cranial nerve I to the olfactory bulb (mitral cells and glomeruli) Submodality coding = “spatiotemporal pattern in the glomuli of the olfactory bulb.” Class # 9: Sens Mech, Smell & Taste, p. 11

Routes through CNS CHEMOSENSES: Olfaction (cont’d) Routes of information transfer through the CNS (1) Cranial nerve I  olfactory bulb (mitral cells & glomeruli) (2) From olfactory bulb to parts of paleocortex in the telencephalon, including the:  Amygdala (emotions)  Entorhinnal, pyriform, & orbitofrontal cortex. (3) From there the information goes to  Hypothalamus (emotions, motivations),  Hippocampus (in temporal lobe: memory) Class # 9: Sens Mech, Smell & Taste, p. 12

CHEMOSENSES: TASTE Class # 9: Sens Mech, Smell & Taste, p. 13

Circumvallate Foliate Foliate Fungiform Bitter Salty Sour Sweet Types of papillae CHEMOSENSES: TASTE (cont’d) [ Umami? Carbohydrate? Glutamate? ] Class # 9: Sens Mech, Smell & Taste, p. 14

Which peripheral receptor? CHEMOSENSES: TASTE (cont’d) Class # 9: Sens Mech, Smell & Taste, p. 15

Primary ‘gustatory’ cortex (near region where the mouth is represented) Also to: amygdala, hypothalamus, orbital prefrontal cortex CHEMOSENSES: TASTE (cont’d) Routes of information transfer through the CNS Class # 9: Sens Mech, Smell & Taste, p. 16

CHEMOSENSES: TASTE (cont’d) Routes of information transfer through the CNS Class # 9: Sens Mech, Smell & Taste, p. 17

Don’t forget! I strongly encourage you to read Module 7.3 (p. 215-227) thoroughly. It contains loads of interesting information about smell and taste as well as pheromones and synesthesia! Class # 9: Sens Mech + Taste & Smell., p. 18

Class # 9: Sens Mech,Smell & Taste, p. 1