W11 - Tastes And Perception ✅ Flashcards
What is meant by synaesthesia?
- Stimulation of a particular type which always leads to another perceptual experience
- e.g. seeing coloured letters
- Approximately 1 in 200 people
What is meant by kinaesthesia?
Illusion of speed
Case 1: Steady speed feels slower after a certain amount of time
-> Explanation: nervous system turns down the ‘gain’ (sensitivity) on steady-state inputs
Case 2: Multisensory approach (e.g. vision & speed)
- Painted/raised lines increase awareness of speed
What is meant by multisensory receptive fields?
- Single neurone may respond to more than one modality (senses)
- Posterior parietal cortex – touch, vision, audition
What is the importance of taste perception?
- Chemosenses: taste (gustation) and smell (olfaction)
- Survival value - prevent ingestion of toxins
- Social value - pheremones
What are the core tastes and what cause them?
Each taste bud cell contains taste receptor that respond to each.
- Sweet: sugars (e.g. fructose) & artificial sweeteners (e.g. saccharin)
- Sour: all acids (e.g. citric acid, lactic acid)
- Salty: salts (e.g. table salt - NaCl)
- Bitter: no unique chemical class (e.g. quinine, caffeine)
- Umami: MSG (basically seasoning)
-> Taste map is a myth, the tongue has specific regions that is more sensitive to ALL tastes
What is meant by supertasters?
Supertasters: those who are more sensitive to taste than a regular human and CAN detect ‘tasteless’ substance PROP
-> opposite to hypotasters (tend to be elderly people since less taste buds present)
What are smell & how can we detect them?
We can discriminate up to 10,000 types of molecules for smell (olfaction)
-> Limited by our memory (knowledge)
-> No satisfactory classification of odours (e.g. Henning’s Smell Prism)
2 routes:
1. Orthonasal - inhalation
2. Retronasal - chewing and swallowing (from mouth)
Bottom-up processing of smell perception from receptor to brain?
Smell receptors:
- 350 different types
- Able to discriminate large number of different smells
- Receptors of similar type project to same glomerulus (received cluster of nerve signal)
Route:
1. Chemicals (odorants) bind to receptors
2. Olfactory receptors activate -> send signal
3. Signals are relayed in glomeruli (classify smell)
4. Signals are transmitted to brain region
Top-down processing of smell perception?
- Attention: sniffing
- Effect of labelling (e.g. same odour smells worse when labelled as body odour rather than cheese)
- Effect of learning (classify wine based on smell)
- “Proust effect” - vivid memories brought back by particular smells
- Close linkage between smell and limbic system in brain (e.g. associate certain smell with positive feeling)
How is our taste influence by other senses (eating is a multi-sensory experience)?
Explanation: tongue is well represented in somatosensory cortex
- Touch (texture): many food widely disliked because of their texture
- Touch (pain): chili acts on pain receptor in tongue BUT can be suppressed by tastes (Best: sweet & sour, Worst: bitter)
- Sound:
- food rated as crunchier and fresher when sound is amplified
- food rated as less sweet and salty in presence of background noise (e.g. airplane food) - Vision: food taste better when arranged in an artistic way, oneology students fooled by white wine with red dye
What is meant by multisensory receptive fields?
A single neurone may respond to more than one modality.
Brain parts responsible for multisensory:
1. Orbitofrontal cortex - taste and smell
2. Posterior parietal cortex - touch, vision and audition
How does multisensory integration work?
- Allow detection of weak stimulus in other modality
- Can make sense of an ambiguous
stimulus in another modality - Can alter the quality of a stimulus in
another modality
What are examples of illusions of multisensory integration?
- Ventriloquism (visual -> sound perception)
- McGurk effect (visual -> sound perception)
- Rubber hand illusion (visual -> touch)
- Kinaesthesia (familiarisation with speed, visual -> speed perception)
- Synaesthesia (stimulation of a particularl type leads to another perceptual experience
-> training can lead to increase in IQ
