Chapter 16 Flashcards
What is anosmia?
The lost of smell and taste
What is taste?
Occurs when molecules enter the mouth in solid or liquid form and stimulate receptors on the tongue
What is olfaction?
Occurs when airborne molecules enter the nose and stimulate receptor neurons in the olfactory mucosa
What is flavor?
The impression we experience from the combination of taste and olfaction
How are olfactory and gustation receptors gatekeepers?
They identify things that the body needs for survival and that should therefore be consumed
The detect things that would be bad for the body and therefore be rejected
What are the five basic taste sensations?
Salty, sour, sweet, bitter, umami
What is sweetness associated with?
Compounds that have a nutritive or caloric value
What are papillae?
Structures that make on the ridges and valleys on the tongue
What are fungiform papillae?
Shaped like mushrooms
Found at the tips and sides of the mouth
What are filiform papillae?
Shapes like cones
Found over the entire surface of the tongue
What are foliate papillae?
Within the folds on the side of the tongue and the back of the tongue on the sides
What are circumvallate papillae?
Shaped like flat mounds surrounded by a trench
Found at the back of the tongue
Which papillae do NOT contain taste buds?
Filiform
How are signals from the tongue transmitted to the brain?
The chorda tymapani nerve = front and side of tongue
The glossopharyngeal nerve = back of tongue
The vagus nerve = mouth and throat
The superficial petrosal nerve = soft palate
Where do all of the nerve fibers from the tongue, mouth, and throat make connections in the brain stem?
The nucleus of the solitary tract
What two areas in the frontal lobe are considered to be the primary taste cortex?
The insula and the frontal operculum
What are across-fiber patterns?
Population coding
What is amiloride?
Blocks the flow of sodium ions into taste receptors
What can individual differences in taste be caused by?
Receptor density
The presence of specialized receptors due to genetic factors
What does microsmatic mean?
Having a poor sense of smell
What does macrosmatic mean?
Have a well-developed sense of smell
What is the forced-choice method?
Participants are presented with blocks of two trials
- one trial contains a weak odorant, the other no odorant
The task is to indicate which trial has a stronger smell
The threshold is determined by measuring the concentration that results in a correct response on 75% of trials
What could identifying odors be highly dependent on?
Our ability to retrieve the odor’s name from our memory
What do individuals sensitive to beta-ionone smell as compared to someone insensitive?
Sensitive = fragrant, floral
Insensitive = pungent, acid
What is loss of smell a predictor of?
Alzheimer’s disease
How does COVID cause taste and smell loss?
It attaches to sustentacular cells which support the olfactory sensory neurons
What are some difficulties in classifying odors?
We lack specific language for odor quality
Molecules with similar properties can smell completely different and vice versa
What are odor objects?
Sources of odors including nonfood sources
What is the olfactory mucosa?
Dime-sized region located on the roof of the nasal cavity just below the olfactory bulb
What do odorant molecules come into contact with?
Olfactory receptor neurons located in the mucosa and the surrounding cells
What is calcium imaging?
When an olfactory receptor responds, the concentration of Ca2+ ions increased inside the OR
Calcium imaging measures this increases in calcium ions by soaking olfactory neurons in a chemical that causes the ORN to fluoresce
This can measure how much Ca2+ enters because increased Ca2+ decreases the glow
What is an odorant recognition profile?
The pattern of activation for each odorant
What do glomeruli do?
Each glomeruli collects information about the firing of a particular type of ORN
What are chemotopic maps?
Maps of odorants in the olfactory bulb based on molecular features of odorants such as carbon chain length or functional groups
What are the two main olfactory areas?
The piriform cortex (primary olfactory area) and the orbitofrontal cortex (secondary olfactory area)
How are odorants represented in the piriform cortex?
Odorants that cause activity in specific locations in the olfactory bulb cause widespread activity in the PC resulting in an overlap between activity caused by different odorants
How are odor objects represented in the piriform cortex?
The formation of odor objects involves learning, which links together the scattered activation that occurs for a particular object
After repeated exposure, the same activation pattern occurs continuously resulting in neural connections being formed
What is the Proust effect?
Description of how certain actions unlock memories that had not been thought of in years, now referred to as odor-evoked autobiographical memories
What happens to the brain during odor-evoked autobiographical memories?
The amygdala (involved in emotions and emotional memories) is lose to the olfactory nerve and the hypothalamus (involved in memory storage) is also close
fMRI brain scans show that odor-evoked memories cause higher activity in the amygdala than word-evoked memories
How do food and drink release volatile chemicals that reach the olfactory mucosa?
Following the retronasal route from the mouth through the nasal pharynx
Decreasing airflow does what to flavor?
The flavor of food is reduced
What is oral capture?
food and drink stimulate tactile receptors in the mouth
So, the sensations we experience from both olfactory and taste receptors are referred to the mouth
What are bimodal neurons?
Neurons that respond to more than one sense
Often respond to similar qualities
What is sensory-specific satiety?
refers to the large effect on the odur associated with food eaten during satiety
What are multimodal interactions?
Interactions that involve more than one sense or quality
