Alliesthesia

Alliesthesia ( (alliós) - changed, and (aísthēsis) - sensation, perception ; French : alliesthésie, German : Alliästhesie) describes the dependence of the perception of pleasure or disgust perceived when consuming a stimulus on the "milieu intérieur" of the organism. Therefore, a stimulus capable of ameliorating the state of the interior milieu, will be perceived as pleasant. In contrary, a stimulus disturbing the milieu interne of the organism will be perceived as unpleasant or even painful. The sensation elicited therefore depends not only on the quality or on the intensity of the stimulus, but also on internal receptors, and is subjective.

Alliesthesia is a physiologic phenomenon and should not be confounded with the pathologic symptom of allesthesia. Another phenomenon based on sensory cues and not to be confound with alliesthesia is "sensory-specific satiety".

Forms of alliesthesia

 * thermic alliesthesia: alliesthesia of the thermic perception (heat and cold) - she contributes fundamentally to homeostatic thermoregulation
 * olfactory alliesthesia: alliesthesia of olfaction (sense of smell)
 * gustatory alliesthesia: alliesthesia of taste - see primary tastes (sweet, salty, bitter, acid, umami and "calcium" )
 * olfacto-gustatory alliesthesia or alimentary alliesthesia: alliesthesia of tastes/flavors pertaining to food intake
 * visual/optic alliesthesia: alliesthesia of vision
 * auditory alliesthesia: alliesthesia of the sense of hearing

Each of these forms of alliesthesia exists in two opposite tendencies:
 * negative alliesthesia: transformation of the sensation from pleasure to displeasure
 * positive alliesthesia: transformation of the sensation from displeasure to pleasure

Discovery
The founder of the phenomenon of alliesthesia is the French physiologist Michel Cabanac. The first scientific publication from 1968 was succeeded by over 40 publications in international journals, for example: 1970 in Nature and 1971 in Science. The term alliesthesia was first mentioned in the annex of Physiological Role of Pleasure and has been chosen in collaboration with the coauthor Stylianos Nicolaïdis. Originally, alliesthesia has been discovered by experiments in human subjects, and later been confirmed in rats (Rattus norvegicus).