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.
Pleasure centers or "hedonic hotspots" are a set of brain structures within the reward system that are directly responsible for mediating the "liking" or pleasure component of an intrinsic reward, as opposed to brain structures that activate in correlation with or as a consequence of the perception of pleasure. Various compartments within the nucleus accumbens, ventral pallidum, and parabrachial nucleus have been identified as pleasure centers which respond to a variety of pleasurable stimuli. The orbitofrontal cortex and insular cortex likely contain hedonic hotspots as well. The anterior cingulate cortex, ventral tegmental area, and amygdala have also been observed to activate in functional neuroimaging studies in response to pleasurable stimuli, but these structures do not necessarily contain hedonic hotspots.
Pleasure is considered to be one of the core dimensions of emotion. It can be described as the positive evaluation that forms the basis for several more elaborate evaluations such as "agreeable" or "nice". As such, pleasure is an affect and not an emotion, as it forms one component of several different emotions. Pleasure is sometimes subdivided into fundamental pleasures that are closely related to survival (food, sex, and social belonging) and higher-order pleasures (e.g., viewing art and altruism). The clinical condition of being unable to experience pleasure from usually enjoyable activities is called anhedonia. An active aversion to obtaining pleasure is called hedonophobia.
Pleasure is often regarded as a bipolar construct, meaning that the two ends of the spectrum from pleasant to unpleasant are mutually exclusive. This view is e.g. inherent in the circumplex model of affect. Yet, some lines of research suggest that people do experience pleasant and unpleasant feelings at the same time, giving rise to so-called mixed feelings.
The degree to which something or someone is experienced as pleasurable not only depends on its objective attributes (appearance, sound, taste, texture, etc.), but on beliefs about its history, about the circumstances of its creation, about its rarity, fame, or price, and on other non-intrinsic attributes, such as the social status or identity it conveys. For example, a sweater that has been worn by a celebrity will be more desired than an otherwise identical sweater that has not, though considerably less so if it has been washed. Another example was when Grammy-winning, internationally acclaimed violinist Joshua Bell played in the Washington D.C. subway for 43 minutes, attracting little attention from the 1,097 people who passed by, and earning about $59 in tips. Paul Bloom describes these phenomena as arising from a form of essentialism.
Epicurus and his followers defined the highest pleasure as the absence of suffering and pleasure itself as "freedom from pain in the body and freedom from turmoil in the soul". According to Cicero (or rather his character Torquatus) Epicurus also believed that pleasure was the chief good and pain the chief evil.
In the 12th century Razi's "Treatise of the Self and the Spirit" (Kitab al Nafs Wa'l Ruh) analyzed different types of pleasure, sensuous and intellectual, and explained their relations with one another. He concludes that human needs and desires are endless, and "their satisfaction is by definition impossible."
In the past, there has been debate as to whether pleasure is experienced by other animals rather than being an exclusive property of humankind; however, it is now known that animals do experience pleasure, as measured by objective behavioral and neural hedonic responses to pleasurable stimuli.
Rewards induce approach behavior, also called appetitive or preparatory behavior, and consummatory behavior. ... Thus any stimulus, object, event, activity, or situation that has the potential to make us approach and consume it is by definition a reward. ... Rewards can also be intrinsic to behavior (31, 546, 547). They contrast with extrinsic rewards that provide motivation for behavior and constitute the essence of operant behavior in laboratory tests. Intrinsic rewards are activities that are pleasurable on their own and are undertaken for their own sake, without being the means for getting extrinsic rewards. We may even generate our own rewards through internal decisions. Mice in the wild enter wheels and run on them on repeated occasions without receiving any other reward or benefit, like the proverbial wheel running hamster (358). Movements produce proprioceptive stimulation in muscle spindles and joint receptors, touch stimulation on the body surface, and visual stimulation from seeing the movement, all of which can be perceived as pleasurable and thus have reward functions. Intrinsic rewards are genuine rewards in their own right, as they induce learning, approach, and pleasure, like perfectioning, playing, and enjoying the piano. Although they can serve to condition higher order rewards, they are not conditioned, higher order rewards, as attaining their reward properties does not require pairing with an unconditioned reward. Other examples for intrinsic rewards are exploration, own beauty, gourmet eating, visiting art exhibitions, reading books, taking power and control of people, and investigating the natural order of the world.
A major goal for affective neuroscience is to identify which brain substrates cause pleasure, whether subjective or objective. Neuroimaging and neural recording studies of have found that rewards ranging from sweet taste to intravenous cocaine, winning money or a smiling face activate many brain structures, including orbitofrontal cortex, anterior cingulate and insula, and subcortical structures such as nucleus accumbens, ventral pallidum, ventral tegmentum, and mesolimbic dopamine projections, amygdala, etc. [4o,5,6,7oo,8,9o,10o,11-13]. But which of those brain systems actually cause the pleasure of the reward? ...
Pleasure is sometimes assumed to be a purely subjective feeling. But pleasure also has objective features in the form of measurable hedonic reactions, both neural and behavioral, to valenced events. In this review, we denote objective hedonic reactions as ''liking'' reactions (with quotes) to distinguish them from the subjective experience of liking (in the ordinary sense, without quotes). Objective hedonic reactions can be measured in both human and animal neuroscience studies, which together allow some comparisons across species and can lead to a more complete causal picture of how brain systems mediate hedonic impact. ... In the prefrontal cortex, recent evidence indicates that the OFC and insula cortex may each contain their own additional hot spots (D.C. Castro et al., Soc. Neurosci., abstract). In specific subregions of each area, either opioid-stimulating or orexin-stimulating microinjections appear to enhance the number of ''liking'' reactions elicited by sweetness, similar to the NAc and VP hot spots. Successful confirmation of hedonic hot spots in the OFC or insula would be important and possibly relevant to the orbitofrontal mid-anterior site mentioned earlier that especially tracks the subjective pleasure of foods in humans (Georgiadis et al., 2012; Kringelbach, 2005; Kringelbach et al., 2003; Small et al., 2001; Veldhuizen et al., 2010). Finally, in the brainstem, a hindbrain site near the parabrachial nucleus of dorsal pons also appears able to contribute to hedonic gains of function (Söderpalm and Berridge, 2000). A brainstem mechanism for pleasure may seem more surprising than forebrain hot spots to anyone who views the brainstem as merely reflexive, but the pontine parabrachial nucleus contributes to taste, pain, and many visceral sensations from the body and has also been suggested to play an important role in motivation (Wu et al., 2012) and in human emotion (especially related to the somatic marker hypothesis) (Damasio, 2010).
So it makes sense that the real pleasure centers in the brain--those directly responsible for generating pleasurable sensations--turn out to lie within some of the structures previously identified as part of the reward circuit. One of these so-called hedonic hotspots lies in a subregion of the nucleus accumbens called the medial shell. A second is found within the ventral pallidum, a deep-seated structure near the base of the forebrain that receives most of its signals from the nucleus accumbens. ... On the other hand, intense euphoria is harder to come by than everyday pleasures. The reason may be that strong enhancement of pleasure--like the chemically induced pleasure bump we produced in lab animals--seems to require activation of the entire network at once. Defection of any single component dampens the high.