Study of the Human Taste System

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Questions and Answers

What is the purpose of a glucose tolerance test (GTT)?

The GTT is used to assess how the body handles glucose and insulin levels over time.

Identify two types of glucose tolerance tests mentioned in the content.

Oral GTT and Intraperitoneal Injection GTT.

How can rodent models be modified to study physiological states like obesity and diabetes?

Rodent models can be adjusted through regular diet experiences or induced by chemical and genetic methods.

What are detection and recognition thresholds in the context of sensory perception?

Detection threshold is the lowest concentration that can be discriminated from a solvent, while recognition threshold is when a substance is both perceived and identifiable. Signup and view all the answers

Name two low-calorie sweeteners listed in the content.

Saccharin and Sucralose. Signup and view all the answers

What role does modulation of lingual RNA/protein expression play in taste perception?

It influences receptor activity, which can affect how taste stimuli are processed. Signup and view all the answers

What is the significance of the circumvallate and fungiform papillae in taste research?

They are types of taste buds involved in the perception of different flavors. Signup and view all the answers

Discuss the importance of using human studies alongside rodent models in taste research.

Human studies provide insights into actual perceptual experiences while rodent models allow controlled experiments. Signup and view all the answers

How is the gustatory threshold determined in the triangular taste detection method?

The gustatory threshold is determined by the correct identification of the stimulus sample at a given concentration three consecutive times. Signup and view all the answers

In suprathreshold intensity ratings, what is assessed?

Intensity of the same stimulus is assessed on a generalized labeled magnitude scale. Signup and view all the answers

What is the significance of fungiform papillae in taste perception?

Fungiform papillae are significant because they contain taste buds and their abundance may enhance taste signal strength. Signup and view all the answers

What experiment is based on a concentration range between recognition and terminal thresholds?

The suprathreshold intensity ratings experiment takes place in this concentration range. Signup and view all the answers

What sample composition is used in the three-alternative forced-choice procedure?

The sample composition consists of two control samples (water) and one stimulus sample. Signup and view all the answers

What does a higher quantity of fungiform papillae suggest about taste perception?

A higher quantity of fungiform papillae suggests a stronger signal being sent centrally, resulting in more intense taste perception. Signup and view all the answers

What is the expected outcome when a participant successfully identifies taste quality twice consecutively?

The expected outcome is to establish the recognition threshold of the taste at that concentration. Signup and view all the answers

What are the primary functions of the human taste system?

The primary functions are sensory discrimination of taste quality and intensity, motivation related to ingestion, and physiological reflexes to manage ingested substances. Signup and view all the answers

Name the four types of papillae found in the human taste system.

The four types are circumvallate, foliate, filiform, and fungiform papillae. Signup and view all the answers

How do taste receptors influence feeding behavior?

Taste receptors influence feeding behavior by signaling the quality of food, which can motivate or deter ingestion. Signup and view all the answers

What is the role of salivary glands in the taste system?

Salivary glands produce saliva that helps dissolve food particles, enabling taste cells to better detect flavors. Signup and view all the answers

Explain how the nervous system is involved in taste perception.

The nervous system transmits signals from taste detectors to the brain, allowing for the interpretation of flavor and taste quality. Signup and view all the answers

What physiological reflexes are triggered by the taste system?

Physiological reflexes include salivation, digestive enzyme secretion, and changes in gastric motility to prepare for food intake. Signup and view all the answers

In your own words, describe the relationship between taste intensity and motivation to eat.

Higher taste intensity can increase motivation to eat by enhancing the appeal of food, while lower intensity may decrease it. Signup and view all the answers

What differentiates sensory-discriminative functions from motivational functions in the taste system?

Sensory-discriminative functions involve recognizing and interpreting taste qualities, while motivational functions drive the desire to eat or avoid food. Signup and view all the answers

What are biosensor cells and what role do they play in monitoring neurotransmitter release?

Biosensor cells are living cells designed to detect specific substances, and they are used to monitor neurotransmitter release through live imaging experiments. Signup and view all the answers

Name at least three neurotransmitters that can be monitored using biosensor cells.

ATP, serotonin, and acetylcholine are three neurotransmitters that can be monitored using biosensor cells. Signup and view all the answers

How does the short-term two-bottle preference test assess taste sensitivity in rodents?

It compares the intake of a test fluid to that of a control fluid to evaluate taste sensitivity. Signup and view all the answers

In the brief-access taste test, what is the minimum number of times mice are required to drink from each bottle?

Mice are required to drink from each bottle at least 2 times, leading to a total of 14 times for 7 bottles. Signup and view all the answers

What technical mechanism is involved in measuring licking behavior during the brief-access taste test?

A small current passing through the sipper tube changes capacitance when the tongue makes contact, which is recorded digitally. Signup and view all the answers

What is the function of carbenoxolone (cbx) in the context of biosensor cells?

Carbenoxolone acts as a blocker of gap junction channels (Px channels), potentially affecting cell communication. Signup and view all the answers

Explain the significance of using fluorescent dyes in biosensor cells.

Fluorescent dyes are crucial for visualizing and tracking the release of neurotransmitters during experiments. Signup and view all the answers

How does the design of the brief-access taste test minimize post-ingestive effects?

The design allows for quick access to multiple taste stimuli, limiting the influence of digestion on taste preference. Signup and view all the answers

What method is used to stain the anterior part of the tongue during the experiment?

A blue dye applied with a cotton tip. Signup and view all the answers

How is excess saliva removed from the front section of the tongue before the experiment?

Excess saliva is dried using filter paper. Signup and view all the answers

What is the purpose of placing a piece of paper with a 6-mm diameter cut-out over the dyed section?

To standardize the area for counting the papillae. Signup and view all the answers

What role do the two parallel silicone tubes play in the taste delivery system?

One tube delivers water, and the other delivers the taste solution. Signup and view all the answers

How often is the taste stimulus delivered to the tongue in the described setup?

The stimulus is delivered 20 times for 1 second each time. Signup and view all the answers

What is the role of Fura-2 in studying intracellular calcium levels in taste cells?

Fura-2 serves as a dual excitation single emission Ca2+ indicator, allowing researchers to measure physiological cytosolic Ca2+ concentrations based on the ratio of fluorescent emissions at different excitation wavelengths. Signup and view all the answers

What is the purpose of the 1-minute interval in the taste delivery system?

To deliver water alone and provide a period of reset between taste stimuli. Signup and view all the answers

What type of recording is used to monitor the brain’s response during the taste stimulus application?

Electroencephalogram (EEG) recording. Signup and view all the answers

How do isolated animal primary taste cells contribute to our understanding of taste signal transduction?

Isolated primary taste cells are used in ex vivo live imaging experiments to investigate intracellular signal transduction pathways and intercellular communication within taste buds. Signup and view all the answers

Which type of papillae is specifically mentioned to be stained and measured in the experimental procedure?

Fungiform papillae. Signup and view all the answers

What physiological changes are detected using ATP-dependent fluorescence in taste bud studies?

ATP-dependent fluorescence allows the detection of Ca2+ responses in taste buds and isolated taste cells, particularly in response to tastants like quinine. Signup and view all the answers

What are recombinant systems and how are they used in taste research?

Recombinant systems express taste receptors and signaling molecules in non-taste cell lines, facilitating high-throughput studies of receptor structure, binding sites, and sensitivity. Signup and view all the answers

What significance does the increase of concentration in a sweet solution have in recombinant systems?

The increase of concentration in sweet solutions allows researchers to determine the concentration at which a 50% maximum response occurs, indicating taste sensitivity. Signup and view all the answers

In taste perception studies, why is it important to measure fast Ca2+ changes?

Measuring fast Ca2+ changes is crucial for understanding the dynamics of voltage-gated Ca2+ currents that are generated during action potentials in taste cells. Signup and view all the answers

How does apical stimulation with quinine affect Ca2+ levels in taste cells?

Apical stimulation with quinine leads to an increase in Ca2+ levels, as detected by the fluorescence of Ca2+ indicators in taste cells. Signup and view all the answers

What is the relationship between fluorescent emission and intracellular Ca2+ concentration in taste cell studies?

The ratio of fluorescent emissions at two specific excitation wavelengths is directly related to the amount of intracellular Ca2+ concentration in taste cells. Signup and view all the answers

Study Notes

Study of the Taste System

Cutting-edge tools are used to study the physiology of feeding behavior, from animals to humans.
The study uses an M2 P2Food approach.
The presenter is Sandrine Chometton, from the Center for Taste and Feeding Behavior (CSGA) in Dijon, within the Sugars - Perception and Receptors (SuPeR) team.

Overview of the Taste System

The presentation covers the functions, structure, and mechanisms of the human taste system.
The system is involved in quality and intensity perception, promoting or deterring ingestion, and preparing the body to process ingested substances.

Functions of the Taste System

Taste perception includes sensory discrimination of taste quality and intensity.
Taste motivates and influences ingestion decisions (facilitating or rejecting).
Physiological reflexes support proper handling of ingested substances.

Human Taste System

The human taste system involves taste bud receptors, papillae (circumvallate, foliate, filiform, fungiform), nerve signal transmission, and areas in the brain (thalamus, hypothalamus, hippocampus, solitary tract nucleus, gustatory nerves - including chorda tympani, glossopharyngeal, and vagus nerves) involved in processing.
Taste receptors detect various taste substances, including sweet, sour, salty, bitter, and umami.

Five Primary Taste Qualities

Sweet: energy-rich nutrients (sugars); examples include fructose.
Sour: signals maturity of fruits, or bacterial contamination. Example: citric acid.
Salty: maintains electrolyte balance; the chemical is sodium chloride.
Bitter: detects diverse natural toxins. Example: caffeine.
Umami: indicates the presence of protein-rich foods; example: L-glutamate.

The Myth of the Tongue Map

The tongue map, showing specific taste receptors on different parts of the tongue, is inaccurate.
Taste receptors are distributed across the tongue and detect all types of tastes.

Taste Cells

Type II cells release ATP, which triggers the analysis of a response to stimuli.
There are G-protein coupled receptors (GPCRs), and these taste receptors detect molecules like sugars, and amino acids.
Specific ion channels also play a valuable role.

Two Classes of Taste Detectors

Taste detectors fall into two broad classes: ion channels and G-protein coupled-receptors (GPCRs). This shows the diverse molecular mechanisms involved in detecting various tastes.

Primary Cells/ Tissue

Isolated animal primary taste cells, taste buds, and tongue epithelium/slices, used in combination with fluorescent dyes, are utilized for studying intracellular signaling pathways, and intercellular communication.
Tools like Fura-2, a dual excitation single emission calcium indicator, assist in studying calcium concentrations.

Recombinant Systems

Recombinant systems, utilizing plate reader experiments to study receptor structure, binding sites, specificity, and sensitivity, are used in high throughput.
The systems express taste receptors and downstream signalling, loaded with chemical dyes.

Biosensor Cells

Biosensor cells, expressing specific neurotransmitter receptors, monitor the release of neurotransmitters (ATP, serotonin, noradrenaline, GABA, acetylcholine) from taste cells with live imaging.
They are used in detecting the presence and concentration of substances.

Rodent Model

Taste sensitivity and intake are assessed using two methods: a two-bottle preference test and a brief-access taste test.
Conditioned taste aversion is studied by inducing malaise with a specific tastant.
The test examines rodent reaction to tastes, and the physiological state (like obesity or diabetes) affects taste experiences and subsequent behavior. The rodent model explores the modulation of lingual RNA/protein expression and receptor activity.

Chemical Induction

Chemicals are used to induce various conditions like diabetes.
Obesogenic diets are used to induce obesity in various stages of the disease.

Human Studies

Detection and recognition thresholds for certain substances are detailed.
Suprathreshold intensity ratings are evaluated on a generalized scale.
Specific taste papillae (like fungiform papillae) are counted to analyze variations.

Gustatory Evoked Potentials (GEPs)

GEPs measure electrical activity in the brain's gustatory cortex in response to stimuli.
The presentation describes the experimental setup and methods for recording GEPs. The results give insights into the timing and magnitude of neural responses, as well as their relation to stimulus type, sensitivity, perceptual qualities, and cognitive interpretation.

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Description

Explore the intricate functions and mechanisms of the human taste system in this insightful presentation led by Sandrine Chometton. Learn about how taste perception influences feeding behavior, quality and intensity of tastes, and the physiological responses involved. This quiz encompasses cutting-edge research and methodologies in the study of taste.