Drug Addiction - Chemistry and the Brain
Professor Trevor Robbins explains that drug addiction involves chemical and neural processes with dopamine and the nucleus accumbens particularly important.
Well the whole process of addiction is a very complicated one. Addiction to drugs probably occurs at several levels - the cellular/biochemical level, and the neural or brain systems level. We know now how most of the drugs of abuse or addiction actually impact on their initial molecular targets in the brain. We know what the targets are and we know where they are. The important thing, however, to understand is what happens as the drug is given chronically, that is to say repeatedly, and how the brain adapts molecularly to this chronic process. Some people think that as a consequence of chronic drug-taking, certain genes are expressed which changes the functions of the nerve cells in that domain, in that area, perhaps permanently and leads to behavioral patterns that are very rigid hard to change. At another level, the brain systems level, we know that many of these drugs of abuse work ultimately, probably through the dopamine system, as it projects to a structure in the base of the forebrain called the nucleus accumbens. However, although the nucleus accumbens may be the initial site of which drugs of abuse exert their effects, perhaps producing highs and euphoria, as the drug is given chronically, over a long period, the effects of the drug spread to other areas of the brain which we think enhance automatic behaviors including drug addiction, drug-seeking behaviors.
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Professor Trevor Robbins explains that the reward system, where dopamine mediates messages to the nucleus accumbens, is artificially activated by certain drugs.
Professor Trevor Robbins explains that the dopamine system is a group of cells originating in the midbrain whose function may be to prepare the brain to think, move, and anticipate rewards.
Doctor Jon Lieberman discusses three neurotransmitters that have been associated with depression - dopamine, serotonin, and norepinephrine.
Professor Trevor Robbins discusses ADHD in relation to noradrenaline and dopamine, both of which are enhanced by ADHD medications such as Ritalin.
Professor Trevor Robbins discusses the function of a set of structures called the basal ganglia, which seem to be involved in response selection.
The idea that drug addiction is a result of 'learning gone wild' was bolstered by several reports.
Doctor Abraham Zangen point out that dopamine and BDNF levels in the nucleus accumbens and hippocampus of depressed patients are different. Treatment with antidepressants or ECT can impact these differences.
Professor Trevor Robbins discusses how positron emission tomography (PET) works to provide detailed images of brain structure and chemistry.
Professor Trevor Robbins discusses whether ADHD is a disorder of the noradrenaline system.
Doctor Larry Young discusses how vasopressin and oxytocin contribute to the reward system, which can promote behavior such as bonding and drug addiction.