Changes: Reward system

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Biological: Behavioural genetics · Evolutionary psychology · Neuroanatomy · Neurochemistry · Neuroendocrinology · Neuroscience · Psychoneuroimmunology · Physiological Psychology · Psychopharmacology (Index, Outline)

In neuroscience, the reward system is a collection of brain structures which regulate and control behavior by inducing pleasurable effects.

Anatomy

The major neurochemical pathway of the reward system in the brain involves the mesolimbic and mesocortical pathway. Of these pathways, the mesolimbic pathway probably plays the major role, and goes from the ventral tegmental area via the medial forebrain bundle to nucleus accumbens, where mainly dopamine is released. This acts on D2 receptors to inhibit the production of cAMP.

Modulation by drugs

Main article: Drug addiction#Psychological

Almost all drugs causing drug addiction increases the dopamine release in the mesolimbic pathway^[1], e.g. opioids, nicotine, amphetamine, ethanol and cocaine. After prolonged use, psychological drug tolerance and sensitization arises.

Psychological drug tolerance

The reward system is partly responsible for the psychological part of drug tolerance. One explanation of this is a sustained activation of the CREB protein, causing a larger dose to be taken to reach the same effect. In addition, it leaves the user feeling generally depressed and dissatisfied, often leading to a return to the drug for an additional "fix".

Sensitization

Sensitization is an increase the user's sensitivity to the effects of the substance, counter to the effects of CREB. A transcription factor, known as delta FosB, is thought to be involved by activating genes that causes sensitization. The hypersensitivity that it causes is thought to be responsible for the intense cravings associated with drug addiction, and is often extended to even the peripheral cues of drug use, such as related behaviors or the sight of drug paraphernalia.

External links

ja:報酬系

This page uses Creative Commons Licensed content from Wikipedia (view authors).

↑ Rang, H. P. (2003). Pharmacology, page 596, Edinburgh: Churchill Livingstone.

[Rang-1] Rang, H. P. (2003). Pharmacology, page 596, Edinburgh: Churchill Livingstone.

[1]

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 {{BioPsy}}
+In neuroscience, the '''reward system''' is a collection of brain structures which regulate and control behavior by inducing pleasurable effects.
-Reward is an operational concept for describing the positive value an individual ascribes to an object, behavioral act or an internal physical state. Primary rewards include those that are necessary for the survival of the species, such as food, water, and sex. Some people include shelter in primary reward. Secondary rewards derive their value from the primary reward and include [[money]], pleasant touch, beautiful faces, [[music]] etc. The functions of rewards are based directly on the modification of [[behavior]] and less directly on the physical and sensory properties of rewards. Rewards induce [[learning]], approach behaviour and feelings of positive [[emotions]].
+==Anatomy==
+The major neurochemical pathway of the reward system in the brain involves the [[mesolimbic pathway|mesolimbic]] and [[mesocortical pathway]]. Of these pathways, the mesolimbic pathway probably plays the major role, and goes from the [[ventral tegmental area]] via the [[medial forebrain bundle]] to [[nucleus accumbens]], where mainly [[dopamine]] is released. This acts on [[D2 receptors]] to inhibit the production of [[cyclic amp|cAMP]].
+==Modulation by drugs==
+{{Main|Drug addiction#Psychological}}
+Almost all drugs causing [[drug addiction]] increases the dopamine release in the mesolimbic pathway<ref name=Rang> {{cite book |author=Rang, H. P. |title=Pharmacology |publisher=Churchill Livingstone |location=Edinburgh |year=2003 |pages=page 596 |isbn=0-443-07145-4 |oclc= |doi=}} </ref>, e.g. [[opioids]], [[nicotine]], [[amphetamine]], [[ethanol]] and [[cocaine]]. After prolonged use, psychological drug tolerance and sensitization arises.
+===Psychological drug tolerance===
+The reward system is partly responsible for the [[psychological]] part of [[drug tolerance]]. One explanation of this is a sustained activation of the [[CREB]] protein, causing a larger dose to be taken to reach the same effect. In addition, it leaves the user feeling generally depressed and dissatisfied, often leading to a return to the drug for an additional "fix".
+===Sensitization===
+[[Sensitization]] is an increase the user's sensitivity to the effects of the substance, counter to the effects of CREB. A transcription factor, known as [[delta FosB]], is thought to be involved by activating genes that causes sensitization. The hypersensitivity that it causes is thought to be responsible for the intense cravings associated with drug addiction, and is often extended to even the peripheral cues of drug use, such as related behaviors or the sight of drug paraphernalia.
-The Reward System is a collection of brain structures which attempts to regulate and control behavior by inducing pleasurable effects. The major neurochemical pathway of the reward system involves the [[mesocortical pathway|mesocorticolimbic pathway (MCLP)]]. The major chemical in the reward system is [[dopamine]].