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The nucleus accumbens plays an integral role in addiction. Almost every addictive drug of abuse induces the release of dopamine into the nucleus accumbens. [8] [37] [38] The NAc is particularly important for instrumental learning, including cue-induced reinstatement of drug-seeking behavior. [39]
Chemistry, not moral failing, accounts for the brain’s unwinding. In the laboratories that study drug addiction, researchers have found that the brain becomes conditioned by the repeated dopamine rush caused by heroin. “The brain is not designed to handle it,” said Dr. Ruben Baler, a scientist with the National Institute on Drug Abuse.
Substances involved with drug addiction include alcohol, nicotine, marijuana, opioids, cocaine, amphetamines, and even foods with high fat and sugar content. [33] Addictions can begin experimentally in social contexts [34] and can arise from the use of prescribed medications or a variety of other measures. [35]
This black box method, wherein an investigator would administer a drug and examine the response without knowing how to relate drug action to patient response, was the main approach to this field, until, in the late 1940s and early 1950s, scientists were able to identify specific neurotransmitters, such as norepinephrine (involved in the ...
Substance dependence, also known as drug dependence, is a biopsychological situation whereby an individual's functionality is dependent on the necessitated re-consumption of a psychoactive substance because of an adaptive state that has developed within the individual from psychoactive substance consumption that results in the experience of withdrawal and that necessitates the re-consumption ...
An addictive drug is defined as a substance that affects the mesolimbic system directly or indirectly by increasing extracellular levels of dopamine. [ 24 ] Common addictive substances such as cocaine , alcohol , and nicotine have been shown to increase extracellular levels of dopamine within the mesolimbic pathway, preferentially within the ...
Drugs targeting the neurotransmitter of major systems affect the whole system, which can explain the complexity of action of some drugs. Cocaine , for example, blocks the re-uptake of dopamine back into the presynaptic neuron, leaving the neurotransmitter molecules in the synaptic gap for an extended period of time.
Brain imaging studies demonstrates that both types of addiction activate similar regions in the mesolimbic reward pathway, a network linked to motivation and pleasure. [18] Moreover, both involve changes in neurotransmitters, such as dopamine and serotonin, which are responsible for regulating mood, impulse control and reward processing. These ...