PSYC 406 Taste

Health consequences of taste sensation

o Variations in sensory properties of foods and beverages affects food preferences and therefore diet. For instance, some vegetables have a bitter taste and so might be avoided by supertasters. when we are children that sensation of bitter so sucks for parents but as we get older we start to like bitter and veggies that are bitter

Medium Tasters

one gene from mom or dad

Taste processing in the central nervous system - Insular cortex:

- Insular cortex: Primary cortical processing area for taste. The part of the cortex that first receives taste information. - *located in the frontal lobe! o frontal lobe is center for our preferences

Salty

- Salt is made up of two charged particles: sodium (cation)(Na+) and chloride (anion) (Cl-)

mechanism of the miracle berries

- compound called miraculin o binds to the sweet receptor nothing happening but when presents of low or high acidity is bonds to the sweet receptor, so when you have something sour or bitter in your mouth it makes it sweet - psychophysical o the sour receptors are still activated when the miracle berry is working but the sour are going into the background and the sweet receptors are taking over.

Orbitofrontal cortex- subsection of frontal lobe

: The part of the frontal lobe of the cortex that lies above the bone (orbit) containing the eyes. • Receives projections from insular cortex • Involved in processing of temperature, touch, smell, and taste, suggesting it may be an integration area • process information about value assignment and preferences That means our perceptions of taste: we have strong preferences for certain types of foods

Genetic Variation in Bitter- Arthur Fox (1931):

Arthur Fox (1931) discovered that phenylthiocarbamide (PTC) tastes dramatically different to different people. § they randomly discovered it o Bitter taste to some but not to others o 1960s: Started using propylthioracil (PROP) instead of PTC because it is safer

Circumvallate papillae

Circular structures that form an inverted V on the rear of the tongue (three to five on each side). Moundlike structures surrounded by a trench. Much larger than fungiform papillae. located in the groves so like backup to still perceive taste if burn others

_____ papillae are circular, mound-like structures surrounded by a trench that form an inverted "V" on the rear of the tongue.

Circumvallate papillae

Sucrose

Common table sugar; combination of glucose + fructose • not created in nature, has to be created Sucrose is perceived as sweeter than fructose bc it is made of artificial sweetneers.

Fructose

Even sweeter than glucose Fructose is the sweetest organic sweetener.

Four kinds of papillae on the tongue

Filiform papillae Fungiform papillae Foliate papillae Circumvallate papillae

Foliate papillae:

Folds of tissue containing taste buds. Located on the rear of the tongue lateral to the circumvallate papillae, where the tongue attaches to the mouth. protect some taste buds hidden within groves of the tongue

Four flavors

Four flavors o Salt, sweet, sour, bitter umami

Omnivore's dilemma

Humans are omnivores and have many choices of what to eat. Modern humans' need to find a healthy diet amidst dizzying choices available to us today. § Ex: Burgers or ice cream

Fungiform papillae

Mushroom-shaped structures (max diameter 1 mm) distributed most densely on edges of tongue, especially the tip. Average of six taste buds per papilla are buried in the surface. located in front area of tongue multiple taste buds in papliles

What happens when we cannot perceive taste but can still perceive smell?

NO TASTE if not both! - Patient case: Damaged taste, but normal olfaction—could smell lasagna, but had no flavor - Similar effect created in lab: Chorda tympani anesthetized with lidocaine

PTC and PROP

Phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP), chemically related compounds, are probes for genetic variation in bitter taste, although PROP is safer with less sulfurous odor.

Glucose

Principle source of energy for most animals

Taste

Sensations evoked by solutions in the mouth that contact the receptors on the tongue and the roof of the mouth.

Filiform papillae

Small structures on the tongue that provide most of the bumpy appearance. Have no taste function. does not have taste buds but still bumps multiple purposes

_______ is the taste quality produced by the hydrogen ion in foods

Sour

_________ is the taste quality produced by the hydrogen ion in foods

Sour

Which of the following taste sensation is evoked by simple carbohydrates

Sweet

Taste processing in the central nervous system- Pathway:

Taste buds to cranial nerves to thalamus and then to cortex

Chorda tympani

The branch of cranial nerve VII (the facial nerve) that carries taste information from the anterior, mobile tongue (the part you can stick out). - carry nerves from taste buds to brain! • carries information about taste to the brain!

Capsaicin

The chemical that produces the burn in chilis; desensitizes pain receptors. o activates the pain receptors

Flavor

The combination of true taste (sweet, salty, sour, bitter) and retronasal olfaction.

Learning comes in to eating veggies

The nutrients in vegetables are, alas, largely undetectable, so we cannot develop specific hungers for them o We learn to like and dislike foods based on the consequences of consuming them (how they make us feel after eating them) § Evaluative conditioning · Ex: if body needs calcium you crave it o Her dad is in ucrine woman would eat chalk or people would lose their teeth with the lack of calcium § you do have a craving for specific vitamins but mostly it is learning. we do not have receptors for ion, vitamins and things.

retronasal olfactory sensation

The sensation of an odor that is perceived when chewing and swallowing force an odorant in the mouth up behind the palate into the nose.

tastant

any stimulus that can be tasted.

The ability to match the intensities of sensation that come from different sensory modalities is known as

cross- modality matching

Remember: - different papillae's -

do not facilitate different taste · any single bud will have all types of cells within it · at some points it was a beliefs that different

Sour

identical activation with hydrogen (H+) and sodium ions

nontasters

no genes!

A ________ is an individual born without receptors for the bitter PROP or PTC

non taster

Chili Peppers

o Acquisition of chili pepper preference depends on social influences o Restriction of liking to humans o Variability across individuals, depending on number of papillae § certain cultures that have hot even when mild thai food! § some eat it since they are born so they get used to it § adapt to taste and particular sensation of taste

Taste adaptation and cross-adaptation

o All sensory systems show adaptation effects o Constant application of certain stimulus temporarily weakens subsequent perception § Example: Adaptation to salt in saliva affects our ability to taste salt · the receptor that responds to salt will stop detecting it

Omnivore's dilemma- Survival value of taste

o Bitter—might signal poisons o Sour—configured to detect acidic solutions that might harm the body § helps us not to consume too many acidic foods o Sweet and Salty—our bodies need sodium and sugar to survive o Umami — our bodies need protein to survive § but too much can not be very good the taste are innate and the preferences are innate too

Sweet

o Evoked by sugars (simple carbohydrates) (complex carbs break to simple making things sweet as it breaks down)- think bread o Many different sugars taste sweet § Glucose: § Fructose: § Sucrose:

Bitter

o There are thousands of bitter molecules § 25 special molecules to recognize the bitter molecules o Cannot distinguish between tastes of different bitter compounds § it is all bitter Bitter receptors are designated by TAS2R#, where # is the number of the receptor

Cross-adaptation:

o when the taste of one food affects the taste of another § Example: A sour beverage tastes too sour after eating a sweet substance • drink orange juice but ate a piece of lemon before drinking it. The orange juice will taste more sweet after eating the lemon. • Sour before = more sweet • if adapt to salt your sensation of something else will increase

Anatomy and Physiology of the Gustatory System - Taste buds:

onion looking buds) (located in the membrane of tougne) Create neural signals conveyed to brain via taste nerves send impulse to perceive a taste what the receptor resonds to Are embedded in structures—papillae (bumps on tongue) Contain taste receptor cells

______ theory is the theory that deficiency of a given nutrient produces craving for that nutrient

specific hungers

Taste buds and taste receptor cells - different types of taste receptor cells can

taste bud can respond to all given types of taste and so any papillae will respond to all taste

Supertaster

two genes plus the receptors just receptors - in the middle between super and middle Individual who is a taster of PTC/PROP and has a high density of fungiform papillae. o Perceives the most intense taste sensations

Desensitization (chilli pepers)

§ If a food is too hot for your palate, wait for burn to subside after the first mouthful. Your palate will desensitize (from the capsaicin) and you should be able to eat the rest of your meal. § as you eat more and more spicy over time they won't be as spicy to you • the receptors sensitize to the receptors of pain

Omnivore's dilemma- Wisdom of the Body (face expressions)

· Infants' behavior and facial expressions reveal innate preferences for certain foods. · Different flavored foods placed on tips of infants' tongues: o Sweet food evokes a "smilelike" expression followed by sucking. o Sour produces pursing and protrusion of lips. § some kids you give puree of something your facival expression is sour but then the kids want more. o Bitter produces gaping, movements of spitting § spitting food out

The special case of fat

· Like protein, fat is an important nutrient. · Fat molecules evoke tactile sensations like oily, viscous, creamy, etc. · Rats have fatty acid receptors on their tongues and humans may, too. · Digesting fat in the gut produces conditioned preferences for the sensory properties of the food containing fat.

Bitter Perception

· Many bitter substances are poisonous · Ability to "turn off" bitter sensations—beneficial to liking certain vegetables • basically, we get used to it and learn to like the bitter taste · Bitter sensitivity is affected by hormone levels in women, intensifies during pregnancy (natural factor) • stress levels too Mushroom pic

Sweet Perception

· Single receptor responsible for all sweet perception o the sweets will stay the same § the sweet can be weaker or strong but never different sweet, more different flavor o Artificial sweeteners stimulate this receptor as well.

Specific hungers theory:

· The idea that deficiency of a given nutrient produces craving (a specific hunger) for that nutrient. o Cravings for salty or for sweet are associated with deficiencies in those substances. o However, the theory has not been supported for other nutrients, such as vitamins.

Umami

· a newer taste- (Pleasant to humans) • Candidate for fifth basic taste • Induced by Glutamate: Important neurotransmitter present in protein • Part of monosodium glutamate (MSG) § basically glutamate that you can sprinkle onto food • like salting your food but you are adding a certain flavor • Safety issues in human consumption of MSG: § Can lead to numbness, headache, flushing, tingling, sweating, and tightness in the chest if sensitive individuals consume a large amount § For most people, MSG does not pose a problem in small doses • associated with junk food to enhance flavor

Papilaes:

· size, shape and form · number of taste buds within each papilae · number of papillae's

Cross-modality matching

·Ability to match the intensities of sensations that come from different sensory modalities. Used to assess intensity of taste sensations for nontasters, medium tasters, tasters, and supertasters o compare bitter to other modalities § bitter compared to birghtest light or sound of fire · comparing it to light 25 recessive 25 dominant 75% should taste some bitterness

taste pore

• - still within the epithelium protecting it • need that because if not it would be damaged

Salty perception

• Ability to perceive salt is not static. § Low-sodium diets will increase sensitivity to salty foods over time. • Liking for saltiness is not static. § Early and gestational experiences can modify salt preference. salt important for woman to consume for during pregnancy depending on if you are eating a lot of salty things than not salty but if not then salty like the sweetness of coffee!

Connection between taste and smell- Brain imaging studies

• Brain processes odors differently, depending on whether they come from nose or mouth. § Food industry adds sugar to intensify sensation of fruit juice • Increase in sweetness (a pure taste sensation) increases perceived olfactory sensation of fruit • fruit is a flavor - if you increase the one of the combination then the total will be increased • the perception is not the same when smelling vs taste • Increase in sweetness (a pure taste sensation) increases perceived olfactory sensation of fruit and thus flavor.

Sour Perception

• Comes from acidic substances • At high concentrations, acids will damage both external and internal body tissues. • sour has a dynamic where a little is perferable and a lot is not • Dissociate

Gene for PTC/PROP receptors discovered in 2003.

• Individuals with two recessive genes are nontasters of PTC/PROP. • Individuals with one or more of the genes are tasters of PTC/PROP.

Taste versus Flavor: What happens when we cannot perceive taste but can still perceive smell?

• Patient case: Damaged taste, but normal olfaction—could smell lasagna, but had no flavor • if you cant smell you will not experience flavor if vice versea • you need BOTH

Five basic tastes

• Salty • Sour • Bitter • Sweet We are wired to perceive these tastes, they all carry specific evolutionarily adaptive mechanism.

Microvilli:

• Slender projections on the tips of some taste bud cells that extend into the taste pore. • Contain the sites that bind to taste substances