CHAPTER 15 - DRUG USE, DRUG ADDICTION, & THE BRAIN’S REWARD CIRCUITS

Flashcards related to drug use, addiction, and the brain's reward circuits.

Psychoactive drugs

Drugs that influence subjective experience and behavior by acting on the nervous system.

Oral ingestion

Preferred route of administration for many drugs; drugs dissolve in the stomach fluids and are carried to the intestine, where they are absorbed into the bloodstream.

Injection

Drug effects are strong, fast, and predictable; made subcutaneously (SC), intramuscularly (IM), or intravenously (IV).

Inhalation

Some drugs are absorbed into the bloodstream through a network of capillaries in the lungs.

Mucous Membranes

Some drugs can be administered through the mucous membranes of the nose, mouth, and rectum.

Blood-brain barrier

Makes it difficult for many potentially dangerous blood-borne chemicals to pass from the blood vessels to the extracellular space around CNS neurons and glia.

Drug metabolism

Conversion of active drugs to nonactive forms by liver enzymes.

Drug Tolerance

State of decreased sensitivity to a drug that develops as a result of exposure to it.

Dose-response curve

Graph of the magnitude of the effect of different doses of the drug.

Cross tolerance

One drug can produce tolerance to other drugs that act by the same mechanism.

Drug sensitization

Increasing sensitivity to a drug.

Metabolic Tolerance

Results from changes that reduce the amount of the drug getting to its sites of action.

Functional Tolerance

Results from changes that reduce the reactivity of the sites of action to the drug.

Withdrawal Syndrome

Sudden drug elimination after significant amounts have been in the body for a period of time (several days), which triggers adverse physiological reactions.

Physically dependent

Individuals who suffer withdrawal reactions when they stop taking the drug.

Drug-addicted individuals

Habitual drug users who continue to use a drug despite its adverse effects on their health and social life, and despite their repeated efforts to stop using it.

Contingent drug tolerance

Tolerance develops only to drug effects that are experienced (before-and-after design).

Conditioned drug tolerance

Tolerance effects are maximally expressed only when a drug is administered in the same situation in which it has previously been administered.

Conditioned Compensatory Responses

Theory that conditioned stimuli that repeatedly predict drug effects come to elicit greater and greater conditioned compensatory responses.

Exteroceptive stimuli

External, public stimuli, such as the drug-administration environment.

Interoceptive stimuli

Internal, private stimuli.

Nicotine

A major psychoactive ingredient of tobacco, commonly administered through inhalation; affects nicotinic cholinergic receptors in the brain; STIMULANT.

Smoking

Inhaling smoke from burning tobacco (cigarettes, cigars); the most common method of nicotine inhalation.

Vaping

Inhaling vapor that contains nicotine (e-cigarettes).

Tar

Nicotine and some 4000 other chemicals are absorbed through the lungs when a cigarette is smoked.

Smoker’s syndrome

Chest pain, labored breathing, wheezing, coughing, and a heightened susceptibility to respiratory tract infections.

Teratogen

Agent that can disturb normal fetal development.

Drug craving

An affective state in which there is a strong desire for the drug; a major defining feature of addiction.

Alcohol

Diuretic involved in more than 3 million deaths globally; birth defects, ill health, accidents, violence; DEPRESSANT.

Hangover

Syndrome of headache, nausea, vomiting, and tremors experienced after alcohol withdrawal.

Delirium tremens (DT)

Disturbing hallucinations, bizarre delusions, disorientation, agitation, confusion, hyperthermia (high body temperature), tachycardia experienced during alcohol withdrawal.

Korsakoff’s syndrome

Neuropsychological disorder characterized by memory loss, sensory and motor dysfunction, and in advanced stages, severe dementia caused indirectly by alcohol consumption and interacting with thiamine deficiency.

Liver Cirrhosis

Extensive scarring of the liver.

Pancreatitis

Inflammation of the pancreas.

Gastritis

Inflammation of the stomach.

Fetal Alcohol Syndrome

May be developed by offspring of mothers who consumed substantial alcohol during pregnancy, resulting in brain damage, intellectual disability, poor coordination, and/or physical deformity.

Marijuana

Dried flower buds of female Cannabis plants; psychoactive effects largely attributed to THC (delta-9-tetrahydrocannabinol).

Hashish

Dark, corklike material extracted and dried from resin.

THC

Delta-9-tetrahydrocannabinol; largely responsible for the psychoactive affects of marijuana.

Narcotic

Legal term generally used to refer to opioids.

Cannabinoids

Chemicals of the same class as THC included in marijuana; 80+ known.

Stimulants

Drugs whose primary effect is to produce general increases in neural and behavioral activity.

Coca paste

A crude extract made directly from coca leaves, which is eaten.

Cocaine hydrochloride

White powder extracted from coca paste; typically consumed by snorting or by injection.

Crack

The impure residue of cocaine hydrochloride boiled in baking soda; a potent, cheap, smokeable form of cocaine.

Cocaine sprees

Binges in which extremely high levels of cocaine intake are maintained for a day or two.

Cocaine psychosis

Psychotic symptoms experienced during a cocaine spree, which is mistakenly diagnosed as schizophrenia.

Amphetamine psychosis

Psychosis syndrome comparable to cocaine often produced by this d-amphetamine.

Empathogens

Psychoactive drugs that produce feelings of empathy.

Dopamine transporters

Molecules in the presynaptic membrane that normally remove dopamine from synapses and transfer it back into presynaptic neurons.

Opium

The dried form of sap exuded by the seedpods of the opium poppy, containing several psychoactive ingredients.

Opioids

Morphine, codeine, and other drugs that have similar structures or effects that exert their effects by binding to receptors whose normal function is to bind to endogenous opioids.

Endocannabinoids

The endogenous opioid neurotransmitters that bind to opioid receptors; 2 classes: endorphins and enkephalins.

Analgesic

Painkiller.

Laudanum

Popular mixture of opium and alcohol.

Heroin rush

Wave of intense abdominal, orgasmic pleasure that evolves into a state of serene, drowsy euphoria from heroin.

Swiss Heroin Program (1994)

Clinics created for supervised heroin use as part of treatment.

Physical-Dependence Theories of Addiction

Physical dependence traps addicted individuals in a vicious circle of drug taking and withdrawal symptoms (use → withdrawal → use ).

Detoxification

Gradual withdrawal in hospitals.

Positive-Incentive Theories of Addiction

Primary factor in most cases of addiction is the craving for the positive-incentive (expected pleasure-producing) drug properties.

Intracranial Self-Stimulation (ICSS)

Rats, humans, & other species will self-administer weak electrical stimulation to specific brain sites.

Pleasure Centers

Sites capable of mediating Intracranial Self-Stimulation (ICSS).

Mesotelencephalic dopamine system

System of dopaminergic neurons that projects from the mesencephalon (midbrain) into various regions of the telencephalon.

Mesencephalon

Midbrain nuclei including the Substantia nigra and Ventral tegmental area.

Nigrostriatal pathway

The axons of dopaminergic neurons that have their cell bodies in the Substantia nigra to dorsal striatum; degeneration is associated with Parkinson’s disease.

Mesocorticolimbic Pathway

The axons of dopaminergic neurons that have their cell bodies in the Ventral tegmental area to various cortical and limbic sites; axons project to the prefrontal cortex, Limbic system, Amygdala, Septum, and Nucleus Accumbens (nucleus of ventral striatum).

Nucleus Accumbens

Nucleus of ventral striatum.

Drug Self-Administering paradigm

Nonhuman animals press a lever to inject drugs into themselves through cannulas (thin tubes).

Conditioned Place-preference paradigm

Nonhuman animals repeatedly receive a drug in one compartment (drug compartment) of a 2-compartment box; drug-free rat learns to associate one compartment with drug effects. When given a choice later, the time spent in the drug compartment reveals the drug’s rewarding value, independent of immediate drug effects.

Physical-Dependence theory

Addiction = cycle of drug-taking to avoid withdrawal.

Positive-Incentive theory

Addiction driven by craving for pleasure, not withdrawal.

Relapse

Returns to drug-taking habit after a period of voluntary abstinence.

Drug priming

Single exposure to the formerly misused drug to restart addiction.

Incubation of drug craving

Time-dependent increase in cue-induced drug craving and relapse.

Unnatural Housing and Testing Conditions

Addiction is less likely when individuals have alternatives and better environments.

10% rule

Preference of sucrose and self-administering cocaine by rate.

Positive-incentive value (wanting)

Anticipated pleasure → drives compulsive drug seeking.

Hedonic value (liking)

Actual pleasure → often decreases over time.