Reward mesolimbic pathway

Initiation of behaviour Mesolimbic pathway to nucleus accumbens from VTA (AIO) Mesocortical pathways to prefrontal cortex from VTA (AIO) Animals Increases locomotor activity and intracranial self-stimulation Humans Hallucinations, psychoses (reward, reinforcement) Animals Decreases activity and self-stimulation Humans Reduces positive symptoms of schizophrenia D2 ... 

Net effect during acute intoxication Increased secretion of dopamine in the mesolimbic pathway (the reward pathway)... 

Considerable data has been accumulated over the past eight years showing that 5-HTg receptors can modulate the release of dopamine in terminal response of the mesolimbic areas. The mesolimbic dopaminergic system has been involved in the mediation of locomotor activity and has been shown to modulate reward mechanisms. Acute but also chronic in vivo administration of ondansetron failed to modify dopaminergic neuronal activity [140, 141], but an attenuation of dopamine release was evident when dopaminergic pathways were activated first. Thus, 5-HTg receptor antagonists partially reversed the activation of the dopaminergic mesolimbic pathway induced by stress procedures [142], by DiMe-C7... 

The nucleus accumbens is part of the limbic system. It receives dopaminergic input through the mesolimbic system that originates from cell bodies in the ventral segmental area (A 10 cell group). This mesolimbic dopaminergic pathway is part of the reward pathways. Drugs of abuse (cocaine, amphetamine, opiates or nicotine) have been shown to increase the level of dopamine release in these neurons. 

Alterations in dopamine (DA) levels are associated with the rewarding effects of abused substances including cigarettes. Specifically, the mesolimbic DA pathway, which originates in the... 

Outline how the mesolimbic reward pathway is implicated in addiction. 

Dopamine A catecholamine neurotransmitter, involved in mesolimbic reward and other important neural pathways. 

Mesolimbic dopamine pathways are thought to be involved in the rewarding effects of drugs of abuse and an imbalance of this pathway is thought to be causal in psychoses. Several studies have revealed that 5-HT3 receptor antagonists can correct such imbalances. Thus, ondansetron inhibits the behavioural hyperactivity resulting from direct stimulation of this... 

FIGURE 10-9. The dopamine hypothesis of psychosis. Hyperactivity of dopamine neurons in the mesolimbic dopamine pathway theoretically mediates the positive symptoms of psychosis, such as delusions and hallucinations. This pathway is also involved in pleasure, reward, and reinforcing behavior, and many drugs of abuse interact here. 

FIGURE 13—1. The mesolimbic dopamine pathway mediates the psychopharmacology of reward, whether that is a natural high or a drug-induced high. 

We have described the mesolimbic dopamine pathway and the neuropharmacology of reward and have specifically emphasized the mechanism of action of several classes of dmgs of abuse, including stimulants (cocaine and amphetamines), hallucinogens, designer drugs and phencyclidine, nicotine, marijuana, opiates, alcohol, benzodiazepines, and sedative-hypnotics. We have even mentioned how receptors and the mesolimbic dopamine pathway could play a role in the psychopharmacology of obesity. 

The first stage, libido, is linked to desire for sex, or sex drive, and is hypothetically a dopaminergic phenomenon mediated by the mesolimbic dopaminergic reward center (Fig. 14—1). This pathway has already been discussed in Chapter 13 and is well known for being the site of action of drugs of abuse as well as the site of... 

Through the pathways of the mesolimbic system (a term introduced by Ungerstedt in 1971), the basal ganglia provide an interface with limbic brain regions. This interface has been repeatedly implicated in psychiatric diseases, such as schizophrenia and other affective disorders, as well as in reward and addiction. 

Mesolimbic dopaminergic pathway Pathway that is rewarding when stimulated (Cihapter 3). 

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