What is drug addiction? It is drug taking on the part of the individual that is usually excessive, harmful to the individual or his/her social environment, and which therefore presents a significant public health problem. The chapters in this technical review deal with the variety of issues of why drug addiction affects only some of us. As documented in these chapters, many of us are exposed on...

Genetic analysis in the nematode C. elegans has provided important insights into many aspects of neuronal cell biology, including functions related to addiction. Specifically, genetic and molecular screens to have been used to identify molecules involved in long-term responses to drugs of abuse and to analyze the mechanisms underlying their effects on nervous system development, plasticity, and...

For much of the twentieth century, theories of addictive behavior and motivation were polarized between two models. The first model viewed addiction as a moral failure for which addicts are rightly held responsible and judged accordingly. The second model, in contrast, viewed addiction as a specific brain disease caused by neurobiological adaptations occurring in response to chronic drug or alc...

Although dopamine is implicated in the development of addiction, it is unclear how specific dopamine release patterns are involved with drug seeking. Addictive drugs increase tonic dopamine levels on the order of minutes, as well as phasic dopamine release events that occur on a subsecond time scale. Phasic dopamine release is associated with the initiation of goal-directed behaviors, and has b...

The past two decades have witnessed a dramatic accumulation of evidence indicating that the excitatory amino acid glutamate plays an important role in drug addiction and alcoholism. The purpose of this review is to summarize findings on glutamatergic substrates of addiction, surveying data from both human and animal studies. The effects of various drugs of abuse on glutamatergic neurotransmissi...

Accumulating evidence suggests that glutamate, as one of the most important excitatory neurotransmitters in the brain, plays a key role in drug addiction including opioid addiction. There is substantial evidence for glutamatergic projections into mesocorticolimbic dopaminergic neurons, which are associated with opioid psychological dependence and are also the key regions of enhancement effect. ...

The development of addiction involves a transition from casual to compulsive patterns of drug use. This transition to addiction is accompanied by many drug-induced changes in the brain and associated changes in psychological functions. In this article we present a critical analysis of the major theoretical explanations of how drug-induced alterations in psychological function might cause a tran...

Drugs of abuse are able to elicit compulsive drug-seeking behaviors upon repeated administration, which ultimately leads to the phenomenon of addiction. Evidence indicates that the susceptibility to develop addiction is influenced by sources of reinforcement, variable neuroadaptive mechanisms, and neurochemical changes that together lead to altered homeostasis of the brain reward system. Addict...

The main idea in this article is that addiction is a consequence of falling victim to decision failures that lead to preference for the addictive behaviors. Addiction is viewed as valuation disease, where the nervous system overvalues cues associated with drugs or drug-taking. Thus, addiction can be viewed as a diminished capacity to choose. Addicted individuals assign lower values to delayed r...