Palatability
Encyclopedia
Palatability is the hedonic reward
provided by foods or fluids that are agreeable to the "palate
" in regard to the homeostatic satisfaction of nutritional
, water
, or energy
needs. The palatability of a food or fluid, unlike its flavor
or taste
, varies with the state of an individual: it is lower after consumption
and higher when deprived
. Palatability of foods, however, can be learned. It has increasingly been appreciated that this can create a hedonic hunger that is independent of homeostatic needs.
-related processes in the nucleus accumbens
and ventral pallidum. The opioid processes involve mu opioid receptor
s and are present in the rostromedial shell part of the nucleus accumbes on its spiny neuron
s. 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
. Unlike the liking palatability for food, the incentive salience 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.
The cessation of a desire to eat after a meal "satiation" is likely to be due different processes and cues. More palatable foods reduce the effects of such cues upon satiation causing a larger food intake.
Reward system
In neuroscience, the reward system is a collection of brain structures which attempts to regulate and control behavior by inducing pleasurable effects...
provided by foods or fluids that are agreeable to the "palate
Palate
The palate is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but, in most other tetrapods, the oral and nasal cavities are not truly separate. The palate is divided into two parts, the anterior...
" in regard to the homeostatic satisfaction of nutritional
Nutrition
Nutrition is the provision, to cells and organisms, of the materials necessary to support life. Many common health problems can be prevented or alleviated with a healthy diet....
, water
Fluid balance
Fluid balance is the concept of human homeostasis that the amount of fluid lost from the body is equal to the amount of fluid taken in. Euvolemia is the state of normal body fluid volume. Water is necessary for all life on Earth...
, or energy
Food energy
Food energy is the amount of energy obtained from food that is available through cellular respiration.Food energy is expressed in food calories or kilojoules...
needs. The palatability of a food or fluid, unlike its flavor
Flavor
Flavor or flavour is the sensory impression of a food or other substance, and is determined mainly by the chemical senses of taste and smell. The "trigeminal senses", which detect chemical irritants in the mouth and throat as well as temperature and texture, are also very important to the overall...
or taste
Taste
Taste is one of the traditional five senses. It refers to the ability to detect the flavor of substances such as food, certain minerals, and poisons, etc....
, varies with the state of an individual: it is lower after consumption
Eating
Eating is the ingestion of food to provide for all organisms their nutritional needs, particularly for energy and growth. Animals and other heterotrophs must eat in order to survive: carnivores eat other animals, herbivores eat plants, omnivores consume a mixture of both plant and animal matter,...
and higher when deprived
Hunger
Hunger is the most commonly used term to describe the social condition of people who frequently experience the physical sensation of desiring food.-Malnutrition, famine, starvation:...
. Palatability of foods, however, can be learned. It has increasingly been appreciated that this can create a hedonic hunger that is independent of homeostatic needs.
Brain mechanism
The palatability of a substance is determined by opioid receptorOpioid receptor
Opioid receptors are a group of G protein-coupled receptors with opioids as ligands. The endogenous opioids are dynorphins, enkephalins, endorphins, endomorphins and nociceptin. The opioid receptors are ~40% identical to somatostatin receptors...
-related processes in the nucleus accumbens
Nucleus accumbens
The nucleus accumbens , also known as the accumbens nucleus or as the nucleus accumbens septi , is a collection of neurons and forms the main part of the ventral striatum...
and ventral pallidum. The opioid processes involve mu opioid receptor
Mu Opioid receptor
The μ-opioid receptors are a class of opioid receptors with high affinity for enkephalins and beta-endorphin but low affinity for dynorphins. They are also referred to as μ opioid peptide receptors. The prototypical μ receptor agonist is the opium alkaloid morphine; μ refers to morphine...
s and are present in the rostromedial shell part of the nucleus accumbes on its spiny neuron
Medium spiny neuron
The medium spiny neurons are a special type of inhibitory cells representing approximately 90% of the neurons within the corpus striatum of the basal ganglia. They play a key role in initiating and controlling movements of the body, limbs, and eyes....
s. 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
Opioid receptor
Opioid receptors are a group of G protein-coupled receptors with opioids as ligands. The endogenous opioids are dynorphins, enkephalins, endorphins, endomorphins and nociceptin. The opioid receptors are ~40% identical to somatostatin receptors...
-related processes in the basolateral amygdala
Basolateral Amygdala
The Basolateral Amygdala is a major limbic-related region within the brain.The basolateral amygdala projects heavily to the nucleus accumbens. The nucleus accumbens is regarded as the limbic-motor interface, in view of these limbic afferent and its somatomotor and autonomic efferent connections...
. Unlike the liking palatability for food, the incentive salience 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 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 ingestation. 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 different processes and cues. More palatable foods reduce the effects of such cues upon satiation causing a larger food intake.
See also
- AppetiteAppetiteThe appetite is the desire to eat food, felt as hunger. Appetite exists in all higher life-forms, and serves to regulate adequate energy intake to maintain metabolic needs. It is regulated by a close interplay between the digestive tract, adipose tissue and the brain. Decreased desire to eat is...
- FlavorFlavorFlavor or flavour is the sensory impression of a food or other substance, and is determined mainly by the chemical senses of taste and smell. The "trigeminal senses", which detect chemical irritants in the mouth and throat as well as temperature and texture, are also very important to the overall...
- Food cravingFood cravingA food craving is an intense desire to consume a specific food, stronger than simply normal hunger. According to Marcia Levin Pelchat "It may be the way in which foods are consumed A food craving is an intense desire to consume a specific food, stronger than simply normal hunger. According to...
- MotivationMotivationMotivation is the driving force by which humans achieve their goals. Motivation is said to be intrinsic or extrinsic. The term is generally used for humans but it can also be used to describe the causes for animal behavior as well. This article refers to human motivation...
- NutritionNutritionNutrition is the provision, to cells and organisms, of the materials necessary to support life. Many common health problems can be prevented or alleviated with a healthy diet....
- Pleasure centerPleasure centerPleasure center is the general term used for the brain regions involved in pleasure. Discoveries made in the 1950s initially suggested that rodents could not stop electrically stimulating parts of their brain, mainly the nucleus accumbens, which was theorized to produce great pleasure...
- TasteTasteTaste is one of the traditional five senses. It refers to the ability to detect the flavor of substances such as food, certain minerals, and poisons, etc....
External links
- The effect of palatability on satiety Martin R Yeomans