Lecture 24 The Chemical Senses

Question 1

What does macrosmatic mean?

Answer 1

keen sense of smell for survival

Question 2

What does microsmatic mean?

Answer 2

less keen sense of smell NOT crucial for survival

Question 3

TRUE or FALSE: animals are macrosmatic, while humans are microsmatic

Answer 3

TRUE

Question 4

What are pheromones?

Answer 4

molecules emitted by members of a species that results in a specific reaction in, or communication with, another individual of the same species

Question 5

what is anosmia?

Answer 5

loss of smell

Question 6

TRUE or FALSE: dogs are more sensitive than rats to odours, and both are more sensitve than humans

Answer 6

TRUE

Question 7

TRUE or FALSE: individual receptors for all animals are equally sensitive to odours

Answer 7

TRUE

Question 8

TRUE or FALSE: humans have more olfactory receptors than dogs

Answer 8

FALSE: dogs have 1 billion, humans have 10 million

Question 9

TRUE or FALSE: humans can IDENTIFY odours better than they can DISCRIMINATE

Answer 9

FALSE: discriminate>identify

Question 10

TRUE or FALSE: individual molecules have individual odours, and we can perceive each one

Answer 10

FALE: we do NOT typically perceive them

Question 11

TRUE or FALSE: some molecules that have similar structures smell different

Answer 11

TRUE

Question 12

TRUE or FALSE: some molecules with different structures smell the same

Answer 12

TRUE

Question 13

Where is the olfactory mucosa?

Answer 13

above the nasal cavity, below the olfactory bulb

Question 14

Odourants are carried via ____________ entering the nose and come into contact with the _______________ embedded in the __________, which contain individual _____________ sensitive to a narrow range of odourants (tuned).

Answer 14

an airstream; olfactory receptor neurons (ORN); mucosa; receptors

Question 15

TRUE or FALSE: each ORN consists of multiple types of receptors

Answer 15

FALSE: one ORN, one type receptor

Question 16

Describe the combinational code for odour.

Answer 16

odourants are codded by PATTERNS OF ACTIVATION OF ORs called RECOGNITION PROFILES

Question 17

TRUE or FALSE: molecules that have similar structures but smell different have similar recognition profiles

Answer 17

FALSE: similar structure, different smell, different recognition profiles

Question 18

What is a parallel between recognition profiles in olfaction and the visual system?

Answer 18

• olfaction: smell coded by patterns of activation of olfactory receptors called recognition profiles
• vision: input from multiple different pigment types create perception of colour

Question 19

Signals are sent from ___________ to the ____________ in the _____________.

Answer 19

ORNs; glomeruli; olfactory bulb

Question 20

TRUE or FALSE: ORNs or a particular type only send their signals to 1 or 2 glomeruli

Answer 20

TRUE

Question 21

what are the 2 techniques that have been used to determine how the glomeruli respond to different odourants?

Answer 21

• optical imaging method
• 2-deoxyglucose (2DG)

Question 22

Describe the optical imaging method for determining how the glomeruli respond to different odourants.

Answer 22

• cortical cells consume oxygen when activated
• red light used to determine the amt of oxygen in the cells
• less oxygen = less red light
• measuring the amt of light reflected reveals which areas of cortex are most active

Question 23

Using optical imaging, the rat olfactory bulb is activated by which 2 kinds of chemicals?

Answer 23

• carbolic acids
• aliphatic alcohols

Question 24

Describe the 2-deoxyglucose method for determining how the glomeruli respond to different odourants.

Answer 24

• 2DG, which contains glucose, is injected into an animal
• animal is exposed to different chemicals
• neural activation is measured by amt of radioactivity present

Question 25

Using 2DG, what is the rat olfactory bulb activated by?

Answer 25

- chemical structure - perception

Question 26

TRUE or FALSE: optical imaging shows that there is chemotopic organization in the olfactory bulb

Answer 26

FALSE: 2DG (not optical imaging)

Question 27

Signals from the olfactory bulb are sent to ____________ in the temporal lobe and amygdala, then _____________ in the frontal lobe.

Answer 27

olfactory bulb --> piriform cortex --> orbitofrontal cortex

Question 28

TRUE or FALSE: the piriform cortex is the secondary olfactory area, whereas the orbitofrontal cortex is the primary olfactory area

Answer 28

FALSE: piriform = primary; orbitofrontal = secondary

Question 29

___________________ causes neural activation across the piriform cortex.

Answer 29

isoamyl acetate

Question 30

TRUE or FALSE: with isoamyl acetate, the systematic pattern in the olfactory bulb is gone

Answer 30

TRUE

Question 31

What is flavour?

Answer 31

combination of smell, taste, and other sensations (e.g. such as burning of hot peppers)

Question 32

Odour stimuli from food in the mouth reaches the olfactory mucosa through the ________________.

Answer 32

retronasal route

Question 33

TRUE or FALSE: The taste of MSG is influenced by olfaction

Answer 33

FALSE: MSG NOT influenced by olfaction

Question 34

review chart on slide 18

Answer 34

slide 18

Question 35

Where are responses from taste and smell first cmbined?

Answer 35

orbital frontal cortex (OFC)

Question 36

Interactions between ___________, ____________, ________, _____________ underscore multimodal nature of our experience of flavour.

Answer 36

taste, olfaction, vision, touch

Question 37

What do bimodal neurons respond to?

Answer 37

more than one sense

Question 38

Where are vision signals sent in terms of flavour.

Answer 38

OFC and amygdala

Question 39

Where are touch signals send in terms of flavour?

Answer 39

OFC and insula

Question 40

Review diagram on slide 20

Answer 40

slide 20

Question 41

Provide an example that demonstrates that OFC modulates its response dpeending on expectations.

Answer 41

wine that is presented as more EXPENSIVE more strongly ACTIVATES the OFC

Question 42

Which neurons are affected by satiety in terms of flavour perception? Describe an example

Answer 42

- omPFC - preference for one type of food could be reflected in more robust firing when that food is consumed, yet ELEVATED RESPONSE TAPERS off as MORE OF THAT FOOD CONSUMED

Question 43

__________ can be a powerful way to induce memory recall.

Answer 43

smell

Question 44

What is the proust effect?

Answer 44

ability of taste and olfaction to cue memories