Chemical Senses

• What is the definition of smell according to Kushner (1993)?

  It’s made up of molecules of what you're smelling
• What do smell and taste require for their function?

  Contact with the molecules they protect from
• How long does neurogenesis take for taste receptors?

  1. 2 weeks
• How long does neurogenesis take for smell receptors?

  1. 7 weeks
• What is one of the primary roles of taste and smell?

  Prepare the body for digestion
• How do taste and smell contribute to food experience?

  They contribute to the flavour of food
• What is the gatekeeper function of taste?

  Identify what the body needs for survival
• What are the four basic tastes?

  Salty, sour, sweet, bitter
• What is the fifth basic taste added later?

  Umami
• What does umami taste like?

  Meaty taste associated with MSG
• What are the types of papillae on the tongue?

  • Filiform: cone shape
  • Fungiform: mushroom shape
  • Foliate: folds
  • Circumvilliate: flat-mounds shape
• Which type of papillae does not contain taste buds?

  Filiform papillae
• How many taste cells does each taste bud contain?

  50-100 taste cells
• Where does transduction occur in the taste system?

  At the taste receptors
• What is the central pathway for taste signals?

  From tongue to nucleus of solitary tract
• What are the primary taste cortical areas?

  Insula and frontal operculum
• What term describes humans' sense of smell?

  Microsmatic
• Why is smell important for many animals?

  It helps them orient in space
• What is a challenge in describing smells?

  Few words exist to describe smells
• What is the detection threshold for T-butyl mercaptan?

  0.3 parts per billion
• What is the role of the olfactory bulb?

  Transmits signals to higher cortical areas
• What is the chemotopic map in the olfactory bulb?

  It represents different odorant activation patterns
• What is the primary olfactory cortex called?

  Piriform cortex
• How does the piriform cortex categorize odours?

  By a process of pattern completion
• What is the relationship between flavour, taste, and smell?

  • Flavour = Taste + Smell
  • Retronasal olfaction: Odorants from oral cavity
  • Orthonasal olfaction: Odorants via the nose
• How does nostril position affect flavour perception?

  Flavour perception varies with nostrils open/closed
• What areas of the brain interact with taste and olfaction?

  Vision, touch, and sounds
• What is the role of the orbitofrontal cortex (OFC) in flavour processing?

  It processes signals from taste and smell
• What are bimodal neurons in the OFC?

  Neurons responding to more than one sense
• How can congruent colours affect taste perception?

  Red enhances sweetness of strawberry beverages
• What are the key references for further reading on chemical senses?

  • Goldstein, E. B. (2010). Sensation and perception.
  • Proust’s “Remembrance of Things Past”.
  • Willander and Larsson (2006) on odour and memory.
  • Auvray and Spence (2007) on multisensory flavour experience.
• What is the significance of Proust’s madeleine in relation to memory?

  It illustrates the link between taste and memory
• How do odour-cued memories compare to other types of memories?

  They are older than word or picture-cued memories
• What brain areas are involved in smell and memory?

  Hippocampus and amygdala
• What is the special link between smell and memory?

  • Odour-cued memories evoke strong emotions
  • Help recall events associated with smell
  • Signals related to smell spread to memory and emotion areas