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Eating is the ingestion of food, typically to provide a heterotrophic organism with energy and to allow for 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 detritivores eat detritus. Fungi digest organic matter outside their bodies as opposed to animals that digest their food inside their bodies. For humans, eating is an activity of daily living. Some individuals may limit their amount of nutritional intake. This may be a result of a lifestyle choice, due to hunger or famine, as part of a diet or as religious fasting.
Appetite is the desire to eat food items, usually due to hunger. Appealing foods can stimulate appetite even when hunger is absent, although appetite can be greatly reduced by satiety. 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. Appetite has a relationship with every individual's behavior. Appetitive behaviour also known as approach behaviour, and consummatory behaviour, are the only processes that involve energy intake, whereas all other behaviours affect the release of energy. When stressed, appetite levels may increase and result in an increase of food intake. Decreased desire to eat is termed anorexia, while polyphagia is increased eating. Dysregulation of appetite contributes to anorexia nervosa, bulimia nervosa, cachexia, overeating, and binge eating disorder.
Satiety is a state or condition of fullness gratified beyond the point of satisfaction, the opposite of hunger. It is a state which induces meal termination. When food is present in the GI tract after a meal satiety signals overrule hunger signals and intake ceases, after which satiety slowly fades as hunger increases.
Motivational salience is a cognitive process and a form of attention that motivates or propels an individual's behavior towards or away from a particular object, perceived event or outcome. Motivational salience regulates the intensity of behaviors that facilitate the attainment of a particular goal, the amount of time and energy that an individual is willing to expend to attain a particular goal, and the amount of risk that an individual is willing to accept while working to attain a particular goal.
Conditioned taste aversion occurs when an animal acquires an aversion to the taste of a food that was paired with aversive stimuli. The Garcia effect explains that the aversion develops more strongly for stimuli that cause nausea than other stimuli. This is considered an adaptive trait or survival mechanism that enables the organism to avoid poisonous substances before they cause harm. The aversion reduces consuming the same substance in the future, thus avoiding poisoning.
The area postrema, a paired structure in the medulla oblongata of the brainstem, is a circumventricular organ having permeable capillaries and sensory neurons that enable its dual role to detect circulating chemical messengers in the blood and transduce them into neural signals and networks. Its position adjacent to the bilateral nuclei of the solitary tract and role as a sensory transducer allow it to integrate blood-to-brain autonomic functions. Such roles of the area postrema include its detection of circulating hormones involved in vomiting, thirst, hunger, and blood pressure control.
Palatability is the hedonic reward provided by foods or fluids that are agreeable to the "palate", which often varies relative 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. It has increasingly been appreciated that this can create a hunger that is independent of homeostatic needs.
Conditioned place preference (CPP) is a form of Pavlovian conditioning used to measure the motivational effects of objects or experiences. This motivation comes from the pleasurable aspect of the experience, so that the brain can be reminded of the context that surrounded the "encounter". By measuring the amount of time an animal spends in an area that has been associated with a stimulus, researchers can infer the animal's liking for the stimulus. This paradigm can also be used to measure conditioned place aversion with an identical procedure involving aversive stimuli instead. Both procedures usually involve mice or rats as subjects. This procedure can be used to measure extinction and reinstatement of the conditioned stimulus. Certain drugs are used in this paradigm to measure their reinforcing properties. Two different methods are used to choose the compartments to be conditioned, and these are biased vs. unbiased. The biased method allows the animal to explore the apparatus, and the compartment they least prefer is the one that the drug is administered in and the one they most prefer is the one where the vehicle is injected. This method allows the animal to choose the compartment they get the drug and vehicle in. In comparison, the unbiased method does not allow the animal to choose what compartment they get the drug and vehicle in and instead the researcher chooses the compartments.
Specific appetite, also known as specific hunger, is a drive to eat foods with specific flavors or other characteristics.
Hunger is a sensation that motivates the consumption of food. The sensation of hunger typically manifests after only a few hours without eating and is generally considered to be unpleasant. Satiety occurs between 5 and 20 minutes after eating. There are several theories about how the feeling of hunger arises. The desire to eat food, or appetite, is another sensation experienced with regards to eating.
Research into food choice investigates how people select the food they eat. An interdisciplinary topic, food choice comprises psychological and sociological aspects, economic issues and sensory aspects.
Sensory specific satiety is a sensory hedonic phenomenon that refers to the declining satisfaction generated by the consumption of a certain type of food, and the consequent renewal in appetite resulting from the exposure to a new flavour or food. The phenomenon was first described in 1956 by the French physiologist Jacques Le Magnen. The term "sensory specific satiety" was coined in 1981 by Barbara J. Rolls and Edmund T. Rolls. The concept illustrates the role of physical stimuli in generating appetite and, more specifically, explains the significance of taste, or food flavour in relation to hunger. Besides conditioned satiety and alimentary alliesthesia, it is one of the three major phenomena of satiation. An Ingestive Classics paper on the topic has been written in conversation with Barbara J. Rolls
David Booth works full-time in research and research teaching as an honorary professor at the School of Psychology in the College of Life and Environmental Sciences of the University of Birmingham (UK). According to his Web page he investigates the ways in which an individual's life works. His research and teaching centre on the processes in the mind that fit acts and reactions of human beings and animals to the passing situation.
Ingestive behaviors encompass all eating and drinking behaviors. These actions are influenced by physiological regulatory mechanisms; these mechanisms exist to control and establish homeostasis within the human body. Disruptions in these ingestive regulatory mechanisms can result in eating disorders such as obesity, anorexia, and bulimia.
Hedonic hunger or hedonic hyperphagia is "the drive to eat to obtain pleasure in the absence of an energy deficit." Particular foods may have a high "hedonic rating" or individuals may have increased susceptibility to environmental food cues. Weight loss programs may aim to control or to compensate for hedonic hunger. Therapeutic interventions may influence hedonic eating behavior.
The term expected satiety refers to the satiety that is expected from a particular food. It is closely associated with 'expected satiation' which refers to the immediate fullness that a food is expected to generate.
In zoology, copulation is animal sexual behavior in which a male introduces sperm into the female's body, especially directly into her reproductive tract. This is an aspect of mating. Many animals that live in water use external fertilization, whereas internal fertilization may have developed from a need to maintain gametes in a liquid medium in the Late Ordovician epoch. Internal fertilization with many vertebrates occurs via cloacal copulation, known as cloacal kiss, while mammals copulate vaginally, and many basal vertebrates reproduce sexually with external fertilization.
Neurogastronomy is the study of flavor perception and the ways it affects cognition and memory. This interdisciplinary field is influenced by the psychology and neuroscience of sensation, learning, satiety, and decision making. Areas of interest include how olfaction contributes to flavor, food addiction and obesity, taste preferences, and the linguistics of communicating and identifying flavor. The term neurogastronomy was coined by neuroscientist Gordon M. Shepherd.
Pavlovian-instrumental transfer (PIT) is a psychological phenomenon that occurs when a conditioned stimulus that has been associated with rewarding or aversive stimuli via classical conditioning alters motivational salience and operant behavior. Two distinct forms of Pavlovian-instrumental transfer have been identified in humans and other animals – specific PIT and general PIT – with unique neural substrates mediating each type. In relation to rewarding stimuli, specific PIT occurs when a CS is associated with a specific rewarding stimulus through classical conditioning and subsequent exposure to the CS enhances an operant response that is directed toward the same reward with which it was paired. General PIT occurs when a CS is paired with one reward and it enhances an operant response that is directed toward a different rewarding stimulus.
Sugar preference is a biological phenomena where sugar is favored over artificial sweeteners by both humans and animals.
References
- ↑ Le Magnen J. Sur le mécanisme d'établissement des appétits caloriques. [Mechanism of establishment of caloric appetites] C. R. Hebd. Séances Acad. Sci. 1955; 240: 2436-38.
- ↑ Booth DA. Conditioned satiety in the rat. J Comp Physiol Psychol. 1972;81(3):457-71.
- ↑ Booth DA, Davis JD. Gastrointestinal factors in the acquisition of oral sensory control of satiation. Physiol Behav. 1973;11(1):23-9.
- ↑ Booth DA. Psychology of Nutrition. London: Taylor & Francis, 1994. 228 pp. full text on google books
- ↑ Booth DA. Learnt reduction in the size of a meal. Measurement of the sensory-gastric inhibition from conditioned satiety. Appetite 2009;52(3):745-9.