Sensation and Perception Chapter 13, Gustation/Taste

varies

sodium content ? from person to person

on the tongue

umami receptors exist ?

Presynaptic Cells

-May transmit information about all five taste dimensions by combination of sour and salt ion channels and ATP activation from sweet, bitter, and umami receptor cells. -ATP directly stimulates cranial nerve endings and presynaptic cells when it is released by receptors encoded by G-Proteins

Similarities of Labeled Lines & Across Pattern Theories to other senses

-Some researchers suggest that the neural coding for taste may function like the visual coding for color (distributed/pattern coding) -Other researchers suggest that the neural coding for taste may function like the auditory coding for pitch (specificity/place coding)

Cranial nerve fibers

-specificity of receptor signals is uncertain - Labeled-line or across-pattern fiber models - Evidence is ambiguous -There is the facial nerve which innervates the front two-thirds of the tongue and soft palate; -the glossopharyngeal nerve which innervates the back one-third of the tongue -the vagus nerve which innervates the epiglottis and the upper esophagus

fungiform papillae

-very front of tongue, contain one or few taste buds -Those with more fungiform papillae experience the most intense taste sensations in general. They also experience the most intense sensations of oral burn (e.g., chilis) and oral touch (fats, thickeners in foods) because fungiform papillae are innervated by trigeminal somatosensory nerve fibers that convey burn and touch sensations, as well as those that convey taste sensations.

sweet, bitter, salty, sour

4 basic tastes proposed by Henning

70%

? of people can taste PTC

gymnema sylvestre

a climbing plant taste modifier found in india and africa

adaptation

a decrease in sensitivity following the continuous presentation of a stimulus

orbitofrontal cortex

a part of the frontal cortex above the eyes, taste information goes here

flavor

a term that includes tastes, smells and tactile experiences

taste modifiers

actually change the taste of other substances

cross adaptation

adaptation to one substance raises the threshold for another substance, you will be less sensitive to the second substance

25 oz

amount of saliva produced each day

gustation

another word for taste

microvilli

at the tip of the taste receptor cells, fill the opening of the taste bud

foliate papillae

back middle of the tongue, contain 100s of taste buds

taste bud

basic receptor for taste stimuli

tastant

basic stimulus for taste, a chemical compound dissolved in a solution such as saliva

aids in digestion, protects from tooth decay

benefits of saliva

higher

both absolute and recognition thresholds are ? for older people

supertasters

can taste PTC as extremely bitter

most, least

citric acids produce the ? saliva, glucose produces the ? saliva

the greeks

defining tastes categories started back with

papillae

different types of small projections (little bumps) on the tongue

gustatory hair

each gustatory receptor has a long, spindle like protrusion that comes in contact with the outside

60 or so

each taste bud contains how many taste receptor cells

umami or savory

fifth tastes that many researchers add to the basic four tastes

sweet, bitter, salty, sour, astringent, pungent, and harsh

first lists of tastes proposed by Aristotle

umami taste

foods that contain glutamate stimulate a ?

volatile

give up vapors, invisible molecule of gas

increase in concentration of sodium ions in saliva

gives rise to our perception of salty tastes

papille

goblet shaped elevations that sometimes contain taste buds and help create friction between the tongue and food

taste pore

gustatory hair extends from ? and mingles with molecules of food introduced by saliva

less bitter, more sweet

higher temperatures make bitter substances taste ? and sweet substances tastes ?

sour or bitter

if you have sweet or salty substances to eat before you drink water, your water can taste

labeled lines

information about taste qualities flows along specific paths to the brain

right side of the brain

information from the right side of the tongue goes to the ?

hedonics

involve judgements of pleasantness and unpleasantness

10 days

life span of taste cells

ageusia

means that a person has lost the ability to taste a substance

miracle fruit

miraculin is a taste modifier found in

supertasters

more sensitive to all tastes and flavors

5,000

most humans have this many taste buds

bitter

most people perceive phenylthiocarbamide (PTC) and 6-n-propylthiouracil as

tongue

muscle covered with mucous membrane

3

nerves in the mouth and throat gather into ? bundles

taste pore

opening of the taste bud

dysgeusia

perceiving a taste that isnt there

transient receptor potential (TRP)

perception of sour tastes involves

taste

perceptions that result from the contact of substances with receptors in the mouth- primarily the tongue

Hans Henning

promoted the idea of 4 basic tastes

total ageusia

rare condition where a person loses the ability to taste anything

higher

recognition thresholds are generally ? than absolute thresholds

G proteins

responsible for our perception of sweet, bitter, and umami Sweet, umami, & bitter tastants are larger molecules encoded by G-protein coupled receptors (GPCR) on receptor cells that release ATP into extracellular space. All have same intracellular signaling mechanism.

umami

savory/meaty flavor cilia have receptor cells with T1R1-T1R3 receptor pairs

mutlidimensional scaling model

schiffman calculated a mutlidimensional odor space, 2 dimensions described odors

trigeminal nerve

sensory system seperate from taste and smell systems, free nerve endings in the mouth and olfactory epithelium

volatile and soluble in fat

smell for an object requires that an object be

mouth feel

somatosensory qualities of foods and drinks

chemical senses

taste and smell are grouped together as ? because they are both sensitive to chemical stimulation

microscope

taste buds are only visible with a ?

taste receptor cells

taste buds contain ? which is arranged like the segments of an orange

age

taste perception declines with

does not get better

taste sensitivity ? with hunger

more rounded

tasters have ? taste buds on their tongues

absolute threshold

tells us whether or not a person can detect the presence of a substance, even if he or she can't identify the taste

tongue map

that specific regions of the tongue are sensitive to different taste qualities

blind spot

the central spot on the tongue lacks tastebuds and is therefore called a

recognition threshold

the concentration of a solution that can be identified by quality

difference threshold

the difference between two stimuli that a person can just barely tell apart

the nucleus of the solitary tract

the nerves in the mouth area travel to an area of the medulla called

soluble

to be tasted an item must be?

sour

tongue map states that the back edges of the tongue tastes? -Sour and salty tastants are transduced by entering ion channels in presynaptic cells that release transmitters at synapses with cranial nerve endings. -one type of sour channel

salty

tongue map states that the front of the tongue tastes? -Sour and salty tastants are transduced by entering ion channels in presynaptic cells that release transmitters at synapses with cranial nerve endings. 2 types of ion channels for salty

sweet

tongue map states that the tip of the tongue tastes? cilia of sweet receptor cells have t1r2-t1r3 receptor pairs

bitter

tongue map states that the very back of the tongue tastes? -cilia w/ receptor cells w. T2R receptors -Bitter tastants are transduced by any of 25-30 individual T2R-type GPCRs on receptor cells. -These don't produce different bitter tastes but allow sensitivity to a wide range of bitter compounds (potential poisons).

cross fiber pattern theory of taste quality

uniqueness (taste quality) of tastes is calculated by the pattern of sensations across a population of receptors (taste fibers)

soluble in fat

vapor molecules must be absorbable by substances containing fat

circumvallate papillae

very back of the tongue, contain 1,000s of taste buds

water taste

water can have a distinct taste when your tongue has been adapted to another taste

medical conditions, stroke, drugs, head trauma

what causes ageusia?

encode taste quality

what do taste receptor cells do

encode texture, shape, temperature and pain

what do trigeminal nerves do?

medical conditions or treatments

what leads to dysgeusia

self adaptation

when the same tastant leads to a loss of sensitivity to itself