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Pleasure describes the 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 account 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, sex or defecation. Other pleasurable experiences are associated with social experiences and social drives, such as the experiences of accomplishment, recognition, and service. The appreciation of cultural artifacts and activities such as art, music, dancing, and literature is often pleasurable. In recent years, significant progress has been made in understanding the brain mechanisms underlying pleasure. One of the key discoveries was made by Kent C. Berridge who has shown that pleasure is not a unitary experience. Rather, pleasure consists of multiple brain processes including liking, wanting and learning subserved by distinct yet partially overlapping brain networks.〔Berridge, K.C., Kringelbach, M.L. (2008) Affective neuroscience of pleasure: Reward in humans and other animals. Psychopharmacology 199, 457–80.〕 In particular, this research has been helped by the use of objective pleasure-elicited reactions in humans and other animals such as the behavioral ‘liking’/‘disliking’ facial expressions to tastes that are homologous between humans and many other mammals.〔(【引用サイトリンク】title=Kent Berridge Biopsychology Lab: Action Syntax & Neuroethology Research )〕 Recreational drug use can be pleasurable: some drugs, illicit and otherwise, directly create euphoria in the human brain when ingested. The mind's natural tendency to seek out more of this feeling (as described by the pleasure principle) can lead to dependence and addiction. Berridge and Robinson have proposed that addiction results from drugs hijacking the ‘wanting’ system through a sensitization of the mesolimbic dopamine system.〔Robinson, T.E., Berridge, K.C. 1993 The neural basis of drug craving: an incentive-sensitization theory of addiction. Brain Res Brain Res Rev. 18(3):247-91.〕 ==Neurobiology== The pleasure center is the set of brain structures, predominantly the nucleus accumbens, theorized to produce great pleasure when stimulated electrically. Some references state that the septum pellucidium is generally considered to be the pleasure center, while others mention the hypothalamus when referring to the pleasure center for intracranial stimulation.〔Kandel ER, Schwartz JH, Jessell TM. ''Principles of Neural Science'', 4th ed. McGraw-Hill, New York (2000). ISBN 0-8385-7701-6〕 Certain chemicals are known to stimulate the pleasure centers of the brain. It has been suggested that physical exertion can release endorphins in what is called the runner's high, and equally it has been found that chocolate and certain spices, such as from the family of the chilli, can release or cause to be released similar psychoactive chemicals to those released during sexual acts. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「pleasure」の詳細全文を読む スポンサード リンク
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