Principles of sensory science:
Lecture 1:
Sense of smell:
Functions:
1. Food/flavour
2. Social life
a. Perfumes/hygiene
b. Pheromones
c. Emotions and memory
3. Safety
4. Symptoms of disease
Family of odor receptor genes >1000 genes (GPCR). 350-400 functional genes, detect more.
Receptors recognize only small parts on molecule
Combination of activated receptors is responsible for smell
Multiple odorants can activate multiple receptors. Pattern of activated glomeruli codes for odor
identity.
1. Ipsilateral: smell on leftside > brain activation on left side
2. Not through thalamus nut straight to periform cortex (primary olfactory cortex) > Secondary
cortex (orbital prefrontal cortex) > insula (taste)
, 3. Overlapping activation but unique patterns per odor in the periform cortex.
4. Smell is dependent upon experience
Odor perception and measurement: Plato: pleasant vs unpleasant (subjective)
Measuring olfactory function:
1. Sniffin sticks: identification, discrimination, detection
2. UPSIT: identification
3. Olfactometer
Odor sensitivity: poor intensity ration (large just-noticeable-difference)
Humans are good at discriminating, structurally similar odors more difficult
Factors influencing olfactory ability:
1. Age
2. Gender
3. Smoking
4. Disease/medication
5. Genetics
6. Size (olfactory bul band nasal volume)
Sniffing and smelling: sniff duration more important than strength
Dual role of olfaction: Orthonasal: external smells, retronasal: internal, flavour, weaker
Olfactory dysfunction: 20% with smell loss > ageing, infection, trauma. Impact on independence, QoL
Trigeminal system: chemical irritation in nose and mouth > pepper, mint, wasabi
Trigeminal nerve endings in eyes, nose, mouth:
1. Brainstem (trigeminal nucleus)
2. Primary somatosensory cortex
3. Secondary somatosensory cortex
Odor interactions: odor impacts taste perception and vice versa. Congruency!
Lecture 2:
Sense of taste
Quality and function of taste:
1. Sweet (sucrose): detecting energy content
2. Salt (NaCl): maintaining electrolyte balance
3. Bitter (Quinine): warning
4. Sour (citric acid): guarding pH level
5. Umami (MSG): motivating protein intake
Functions: Gatekeeper of internal system, each taste associated with physical function
Anatomy: More papillae at front of tongue so more sensitive to taste
Tongue > gustatory papillae > taste buds > taste receptor (50 per bud)
Lecture 1:
Sense of smell:
Functions:
1. Food/flavour
2. Social life
a. Perfumes/hygiene
b. Pheromones
c. Emotions and memory
3. Safety
4. Symptoms of disease
Family of odor receptor genes >1000 genes (GPCR). 350-400 functional genes, detect more.
Receptors recognize only small parts on molecule
Combination of activated receptors is responsible for smell
Multiple odorants can activate multiple receptors. Pattern of activated glomeruli codes for odor
identity.
1. Ipsilateral: smell on leftside > brain activation on left side
2. Not through thalamus nut straight to periform cortex (primary olfactory cortex) > Secondary
cortex (orbital prefrontal cortex) > insula (taste)
, 3. Overlapping activation but unique patterns per odor in the periform cortex.
4. Smell is dependent upon experience
Odor perception and measurement: Plato: pleasant vs unpleasant (subjective)
Measuring olfactory function:
1. Sniffin sticks: identification, discrimination, detection
2. UPSIT: identification
3. Olfactometer
Odor sensitivity: poor intensity ration (large just-noticeable-difference)
Humans are good at discriminating, structurally similar odors more difficult
Factors influencing olfactory ability:
1. Age
2. Gender
3. Smoking
4. Disease/medication
5. Genetics
6. Size (olfactory bul band nasal volume)
Sniffing and smelling: sniff duration more important than strength
Dual role of olfaction: Orthonasal: external smells, retronasal: internal, flavour, weaker
Olfactory dysfunction: 20% with smell loss > ageing, infection, trauma. Impact on independence, QoL
Trigeminal system: chemical irritation in nose and mouth > pepper, mint, wasabi
Trigeminal nerve endings in eyes, nose, mouth:
1. Brainstem (trigeminal nucleus)
2. Primary somatosensory cortex
3. Secondary somatosensory cortex
Odor interactions: odor impacts taste perception and vice versa. Congruency!
Lecture 2:
Sense of taste
Quality and function of taste:
1. Sweet (sucrose): detecting energy content
2. Salt (NaCl): maintaining electrolyte balance
3. Bitter (Quinine): warning
4. Sour (citric acid): guarding pH level
5. Umami (MSG): motivating protein intake
Functions: Gatekeeper of internal system, each taste associated with physical function
Anatomy: More papillae at front of tongue so more sensitive to taste
Tongue > gustatory papillae > taste buds > taste receptor (50 per bud)
