pleasure
Pleasure refers to experience that feels good, that involves the enjoyment of something. It contrasts with pain
Pain is a distressing feeling often caused by intense or damaging stimuli. The defines pain as "an unpleasant sensory and emo ...
) provided by foods or fluids that are agreeable to the "palate
The palate () is the roof of the mouth
In animal anatomy
Anatomy (Greek ''anatomē'', 'dissection') is the branch of biology concerned with the study of the structure of organism
In biology, an organism (from Ancient Greek, Greek: ...
", which often varies relative to the homeostatic
In biology, homeostasis is the state of steady internal, physics, physical, and chemistry, chemical conditions maintained by organism, living systems. This is the condition of optimal functioning for the organism and includes many variables, such ...
satisfaction of nutrition
Nutrition is the biochemical and physiological process by which an organism uses food to support its life. It includes ingestion, Absorption (biology), absorption, Assimilation (biology), assimilation, biosynthesis, catabolism and excretion.
...
al, water
Water (chemical formula H2O) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known li ...
, or energy
In physics
Physics is the that studies , its , its and behavior through , and the related entities of and . "Physical science is that department of knowledge which relates to the order of nature, or, in other words, to the regula ...
needs. The palatability of a food or fluid, unlike its flavor
Flavor, or flavour, is the perceptual
Perception (from the Latin
Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area arou ...
or taste
The gustatory system or sense of taste is the sensory system
The sensory nervous system is a part of the nervous system responsible for processing sensory information. A sensory system consists of sensory neurons (including the sensory re ...
, varies with the state of an individual: it is lower after consumption
Consumption may refer to:
*Resource consumption
*Tuberculosis, an infectious disease, historically
in biology:
* Consumption (ecology), receipt of energy by consuming other organisms
in social sciences:
* Consumption (economics), the purchasing of ...
and higher when . It has increasingly been appreciated that this can create a hunger that is independent of homeostatic needs.Lowe MR, Butryn ML. (2007). Hedonic hunger: a new dimension of appetite? Physiol Behav. Jul 24;91(4):432-9.
Brain mechanism
The palatability of a substance is determined by opioid receptor
Opioid receptors are a group of inhibitory G protein-coupled receptor
G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-lin ...
-related processes in the nucleus accumbens
The nucleus accumbens (NAc or NAcc; also known as the accumbens nucleus, or formerly as the ''nucleus accumbens septi'', Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin w ...
and ventral pallidum
The globus pallidus (GP), also known as paleostriatum or dorsal pallidum, is a Cerebral cortex, subcortical structure of the brain. It consists of two adjacent segments, one external, known in rodents simply as the globus pallidus, and one interna ...
.Wassum KM, Ostlund SB, Maidment NT, Balleine BW. (2009). Distinct opioid circuits determine the palatability and the desirability of rewarding events. Proc Natl Acad Sci U S A. 106:12512–12517 The opioid processes involve s and are present in the rostromedial shell part of the nucleus accumbens on its spiny neurons. This area has been called the "opioid eating site".
The rewardfulness of consumption associated with palatability is dissociable from desire or incentive value which is the motivation to seek out a specific commodity. Desire or incentive value is processed by opioid receptor-related processes in the 
basolateral amygdala
The basolateral amygdala (BLA), or basolateral complex, consists of the lateral, basal and accessory-basal nuclei of the amygdala
The amygdala (; plural: amygdalae or amygdalas; also '; Latin from Greek language, Greek, , ', 'almond', 'tonsil ...
. Unlike the liking palatability for food, the incentive salience
An incentive is something that motivates or drives one to do something or behave in a certain way. There are two types of incentives that affect human decision making. These are: intrinsic and extrinsic incentives. Intrinsic incentives are ...
wanting is not downregulated by the physiological consequences of food consumption and may be largely independent of homoeostatic processes influencing food intake.
Though the wanting of incentive salience may be informed by palatability it is independent and not necessarily reduced to it. It has been suggested that a third system exists that links opioid processes in the two parts of the brain: "Logically this raises the possibility that a third system, with which the accumbens shell, ventral pallidum, and basolateral amygdala are associated, distributes the affective signals elicited by specific commodities across distinct functional systems to control reward seeking... At present we do not have any direct evidence for a system of this kind, but indirect evidence suggests it may reside within the motivationally rich circuits linking hypothalamic and brainstem viscerogenic structures such as the parabrachial nucleus.
It has also been suggested that "hedonic hunger" can be driven both in regard to "wanting" and "liking" and that a palatability subtype of neuron may also exist in the basolateral amygdala.
Satiety and palatability
Appetite
Appetite is the desire to eat
Eating (also known as consuming) is the ingestion of food
Food is any substance consumed to provide nutritional support for an organism
In biology, an organism (from Ancient Greek, Greek: ὀργα ...
is controlled by a direct loop and an indirect one. In both the direct and indirect loops there are two feedback mechanisms. First a positive feedback involving its stimulation by palatability food cues, and second, a negative feedback due to satiation and satiety cues following ingestion. In the indirect loop these cues are learnt by association such as meal plate size and work by modulating the potency of the cues of the direct loop. The influence of these processes can exist without subjective awareness.
The cessation of a desire to eat after a meal "satiation" is likely to be due to different processes and cues. More palatable foods reduce the effects of such cues upon satiation causing a larger food intake. In contrast, unpalatability of certain foods can serve as a deterrent from feeding on those foods in the future. For example, the variable checkerspot butterfly contains iridoidImage:Iridomyrmecin.svg, Chemical structure of iridomyrmecin
Iridoids are a type of monoterpenoids in the general form of cyclopentanopyran, found in a wide variety of plants and some animals. They are biosynthesis, biosynthetically derived from 8-o ...
compounds that are unpalatable to avian predators, thus reducing the risk of predation
Predation is a biological interaction
In ecology
Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical en ...
.Bowers, M. D. "Unpalatability as a Defense Strategy of Western Checkerspot Butterflies (Euphydryas Scudder, Nymphalidae)." Evolution 35.2 (1981): 367-75.
See also
*Acquired taste
An acquired taste is an appreciation for something unlikely to be enjoyed by a person who has not had substantial exposure to it. It is the opposite of innate taste, which is the appreciation for things that are enjoyable by most persons without p ...
*Flavor
Flavor, or flavour, is the perceptual
Perception (from the Latin
Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area arou ...
*Food craving
A food craving (also called selective hunger) is an intense desire to consume a specific food, and is different from normal hunger. It may or may not be related to specific hunger, the drive to consume particular nutrients that is well-studied in ...
*Motivation
Motivation is what explains why people or animals initiate, continue or terminate a certain behavior at a particular time. Motivational states are commonly understood as forces acting within the agent that create a disposition to engage in goal-d ...
*Nutrition
Nutrition is the biochemical and physiological process by which an organism uses food to support its life. It includes ingestion, Absorption (biology), absorption, Assimilation (biology), assimilation, biosynthesis, catabolism and excretion.
...
*Pleasure center
Pleasure refers to experience that feels good, that involves the enjoyment of something. It contrasts with pain or suffering, which are forms of feeling bad. It is closely related to value, desire and action: humans and other conscious animals f ...
References
External links
The effect of palatability on satiety
{dead link, date=March 2018 , bot=InternetArchiveBot , fix-attempted=yes Martin R Yeomans Behavioral neuroscience Gustation Gustatory system