I came across this on Wikipedia's Desire -"While desires are often classified as emotions by laypersons, psychologists often describe desires as different from emotions. For psychologists, desires arise from bodily structures and functions (e.g., the stomach needing food and the blood needing oxygen). On the other hand, emotions arise from a person's mental state. A 2008 study by the University of Michigan indicated that, while humans experience desire and fear as psychological opposites, they share the same brain circuit."
Then that made me think of a writing of mine I did many years ago called "Seeking a Emotion"
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
Motivational salience is composed of two component processes that are defined by their attractive or aversive effects on an individual's behavior relative to a particular stimulus: incentive salience and aversive salience. Incentive salience is the attractive form of motivational salience that causes approach behavior, and is associated with operant reinforcement, desirable outcomes, and pleasurable stimuli. Aversive salience is the aversive form of motivational salience that causes avoidance behavior, and is associated with operant punishment, undesirable outcomes, and unpleasant stimuli
Incentive salience is a cognitive process that confers a "desire" or "want" attribute, which includes a motivational component, to a rewarding stimulus. Reward is the attractive and motivational property of a stimulus that induces appetitive behavior – also known as approach behavior – and consummatory behavior. The "wanting" of incentive salience differs from "liking" in the sense that liking is the pleasure that is immediately gained from the acquisition or consumption of a rewarding stimulus; the "wanting" of incentive salience serves a "motivational magnet" quality of a rewarding stimulus that makes it a desirable and attractive goal, transforming it from a mere sensory experience into something that commands attention, induces approach, and causes it to be sought out.
Incentive salience is regulated by a number of brain structures, but it is assigned to stimuli by a region of the ventral striatum known as the nucleus accumbens shell. Incentive salience is primarily regulated by dopamine neurotransmission in the mesocorticolimbic projection,[note 1], but activity in other dopaminergic pathways and hedonic hotspots (e.g., the ventral pallidum) also modulate incentive salience
The assignment of incentive salience to stimuli is dysregulated in addiction. Addictive drugs are intrinsically rewarding (i.e., pleasurable) and therefore function as primary positive reinforcers of continued drug use that are assigned incentive salience. During the development of an addiction, the repeated association of otherwise neutral and even non-rewarding stimuli with drug consumption triggers an associative learning process that causes these previously neutral stimuli to act as conditioned positive reinforcers of addictive drug use (i.e., these stimuli start to function as drug cues). As conditioned positive reinforcers of drug use, these previously neutral stimuli are assigned incentive salience (which manifests as a craving) – sometimes at pathologically high levels due to reward sensitization – which can transfer to the primary reinforcer (e.g., the use of an addictive drug) with which it was originally paired. Thus, if an individual remains abstinent from drug use for some time and encounters one of these drug cues, a craving for the associated drug may reappear. For example, anti-drug agencies previously used posters with images of drug paraphernalia as an attempt to show the dangers of drug use. However, such posters are no longer used because of the effects of incentive salience in causing relapse upon sight of the stimuli illustrated in the posters.
Pleasure is a broad class of mental states that humans and other animals experience as positive, enjoyable, or worth seeking. It includes more specific mental states such as happiness, entertainment, enjoyment, ecstasy, and euphoria. The early psychological concept of pleasure, the pleasure principle, describes it as a positive feedback mechanism, motivating the organism to recreate in the future the situation which it has just found pleasurable and to avoid situations that have caused pain in the past.
The experience of pleasure is subjective and different individuals will experience different kinds and amounts of pleasure in the same situation. Many pleasurable experiences are associated with satisfying basic biological drives, such as eating, exercise, hygiene, and sex. The appreciation of cultural artifacts and activities such as art, music, dancing, and literature is often pleasurable.
Based upon the incentive salience model of reward – the attractive and motivational property of a stimulus that induces approach behavior and consummatory behavior – an intrinsic reward has two components: a "wanting" or desire component which is reflected in approach behavior and a "liking" or pleasure component that is reflected in consummatory behavior. While all pleasurable stimuli are rewards, some rewards do not evoke pleasure.