Chapter 18 – Drug Abuse

Chapter 18 – Drug Abuse - Chapter 18 [1] Chapter 18 Drug...

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Chapter 18 [1] Chapter 18 – Drug Abuse Common Features of Addiction I. A Little Background a. Ethyl alcohol is the earliest drug b. Opium poppy II. Positive Reinforcement a. Lead to dependency that reinforce people’s behavior b. Drugs work by reinforcing effects c. Role in Drug Abuse i. The effectiveness of a reinforcing stimulus is greatest if it occurs immediately after a response occurs ii. Rats chose to take small amount of food delivered right away, immediacy took precedence over quantity iii. Most addictive drugs are those with immediate effects iv. Heroin is most addictive, travels directly to brain v. Immediate reinforcing can overpower recognition of long term aversive effects d. Neural Mechanisms i. Drugs cause release of dopamine in the nucleus accumbens ii. Dopamine appears to be necessary condition for positive reinforcement to take place III. Negative Reinforcement a. Negative Reinforcement – the removal or reduction of an aversive stimulus that is contingent on a particular response, with an attendant increase in the frequency of that response b. Punishment makes a response less likely, reinforcement makes it more likely c. For punishment to occur, the response must make the unpleasant stimulus occur d. Tolerance – the fact that increasingly large doses of drugs must be taken to achieve a particular effect; caused by compensatory mechanisms that oppose the effect of the drug e. Withdrawal symptoms – the appearance of symptoms opposite to those produced by a drug when the drug is suddenly no longer taken; caused by the presence of compensatory mechanisms f. Compensatory mechanisms make themselves felt when person stopped taking the drug, unopposed by the action of the drug IV. Craving and Relapse a. Drug addiction involves a cycle of spiraling dysregulation of brain reward systems that progressively increases, resulting in the compulsive use and loss of control of drug-taking b. Small dose of drug increases craving or appetite for the drug c. Relapses involve activation of the mesolimbic system of dopaminergic neurons d. Drugs that can be abused activate the medial prefrontal cortex and the
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Chapter 18 [2] nucleus acumbens e. People with drug addictions – the prefrontal cortex appears to by hypoactive at rest f. The more cocaine a person takes, the lower the brain activity is g. Show structural abnormalities (drugies) – 11 percent decreases in the gray matter volume of the cingulated cortex h. Negative and cognitive symptoms of schizophrenia appear to be a result of hypofrontality i. Up to half of all people with schizophrenia have a substance abuse disorder j. Whether preexisting abnormalities increase the risk of these disorders or whether the disorders cause the abnormalities has not yet been determined k. Adolescence is a time of rapid and profound maturation change in the brain – particularly in the prefrontal cortex – impulsive behavior, novelty- driven, risky behavior, experimentation with drugs l. Stressful situations can cause former drug addicts to relapse
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This note was uploaded on 02/27/2008 for the course PSYC 326 taught by Professor Chambers,lavond during the Spring '05 term at USC.

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Chapter 18 – Drug Abuse - Chapter 18 [1] Chapter 18 Drug...

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