Drug Addiction and Reward Circuits Flashcards
What is an amphetamine?
a stimulant drug
What is an analgesic?
drugs that reduce pain
What is anandamide?
the first endogenous endocannabinoid to be discovered and characterised
What is anhedonia?
a general inability to experience pleasure
What is a before-and-after design?
the experimental design used to demonstrate contingent drug tolerance; one group receives the drug before each of a series of behavioural tests and the other group receives the drug after each test
What is Buerger’s disease?
a condition in which the blood vessels, especially those supplying the legs, are constricted whenever tobacco is smoked. The disease can progress to gangrene and amputation
What is cannabis?
the common hemp plant, which is the source of marijuana
What is cirrhosis?
scarring of the liver, which is a major cause of death among heavy alcohol users
What is cocaine?
a stimulant that exerts its effects by altering the activity of dopamine transporters
What is cocaine psychosis?
psychotic symptoms that are sometimes observed during cocaine sprees; similar in certain respects to schizophrenia
What are cocaine sprees?
binges of cocaine use
What is codeine?
a relatively weak psychoactive ingredient of opium
What are conditioned compensatory responses?
hypothetical conditional physiological responses that are opposite to the effects pf a drug that are thought to be elicited by stimuli that are regularly associated with experiencing the drug effects
What is a conditioned drug tolerance?
tolerance effects that are maximally expressed only when a drug is administered in the same situation in which it has previously been administered
What is a conditioned place-preference paradigm?
a test that assesses a laboratory animal’s preference for an environment in which it has previously experienced drug effects relative to a control environment
What is a contingent drug tolerance?
drug tolerance that develops as a reaction to the experience of the effects of drugs rather than to drug exposure alone
What is crack?
a potent, cheap, smokable form of cocaine
What is cross tolerance?
tolerance to the effects of one drugs that develops as the result of exposure to another drug that acts by the same mechanism
What is delirium tremens (DTs)?
the phase of alcohol withdrawal syndrome characterised by hallucinations, delusions, disorientation, agitation, confusion, hyperthermia and tachycardia
What is a depressant?
a drug that depressed neural activity
What are dopamine transporters?
molecules in the presynaptic membrane of dopaminergic neurons that attract dopamine molecules in the synaptic cleft and deposit them back inside the neuron
What is a drug addicted individual?
those habitual drug users who continue to use a drug despite its adverse effects on their health and social life and despite their repeated effort to stop using it
What is a drug craving?
an affective state in which there is a strong desire for a particular drug
What is drug metabolism?
the conversion of a drug from its active form to a nonactive form
What is drug priming?
a single exposure to a formerly used drug
What is the drug self-administration paradigm?
a test of the addictive potential of drugs in which laboratory animals can inject drugs into themselves by pressing a lever
What is drug sensitisation?
an increase in the sensitivity to a drug effect that develops as the result of exposure to the drug
What is drug tolerance?
a state of decreased sensitivity to a drug that develops as a result of exposure to the drug
What are empathogens?
psychoactive drugs that produce feelings of empathy
What is exteroceptive stimuli?
stimuli that arise from outside the body
What is fetal alcohol syndrome (FAS)?
a syndrome produced by prenatal exposure to alcohol and characterised by brain damage, intellectual disability, poor coordination, poor muscle tone, low birth weight, retarded growth, and/or physical deformity
What is functional tolerance?
drug tolerance that results from changes that reduced the reactivity of the sites of action to the drug
What was the Harrison Narcotics Act?
the act passed in 1914 that made it illegal to sell or use opium, morphine or cocaine in the United States
What is hashish?
dark cornlike material extracted from the resin on the leaves and flowers of cannabis
What is hedonic value?
the amount of pleasure that is actually experienced as the result of some action
What is heroin?
a semisynthetic opioid
What is the incentive-sensitisation theory?
theory that addictions develop when drug use sensitises the neural circuits mediating wanting of the drug - not necessarily liking of the drug
What is incubation of drug craving?
the time-dependent increase in cueinduced drug craving and relapse
What is interoceptive stimuli?
stimuli that arise from inside the body
What is intracranial self-stimulation (ICSS)?
the repeated performance of a response that delivers electrical stimulation to certain sites in the animal’s brain
What is Korsakoff’s syndrome?
a neuropsychological disorder that is common in alcoholics and whose primary symptoms include memory loss, sensory and motor dysfunction, and, in its advanced stages, severe dementia
What is the mesocorticolimbic pathway?
the component of the mesotelencephalic dopamine system that has cell bodies in the ventral tegmental area that project to various cortical and limbic sites
What is the mesotelencephalic dopamine system?
the ascending projections of dopamine-releasing neurons from the substantia nigra and ventral tegmental area of the mesencephalon into various regions of the telencephalon
What is metabolic tolerance?
tolerance that results from a reduction in the amount of drug getting to its sites of action
What is morphine?
the major psychoactive ingredient in opium
What is a narcotic?
a legal term generally used to refer to opioids
What is nicotine?
the major psychoactive ingredient of tobacco
What is the nucleus accumbens?
nucleus of the ventral striatum and a major terminal of the mesocorticolimbic dopamine pathway
What are opioids?
morphine, codeine, heroin, and other chemicals with similar structures or effects
What is opium?
the sap that exudes from the seed pods of the opium poppy
What does pharmacological mean?
pertaining to the scientific study of drugs
What is the physical-dependence theories of addiction?
theories holding that the main factor that motivated drug-addicted individuals to keep taking drugs is the prevention or termination of withdrawal symptoms
What is physically dependent?
being in a state in which the discontinuation of drug taking will induce withdrawal symptoms
What are positive-incentive theories of addiciton?
theories holding that the primary factor in most cases of addiction is the craving for the positive-incentive (expected pleasure-producing) properties of the drug
What is positive-incentive value?
the idea that behaviours (e.g., eating and drinking) are motivated by their anticipated pleasurable effects
What are psychoactive drugs?
drugs that influence subjective experience and behaviour by acting on the nervous system
What does relapse mean?
the return to one’s drug taking habit after a period of voluntary abstinence
What is smoker’s syndrome?
the chest pain, laboured breathing, wheezing, coughing, and heightened susceptibility to infections of the respiratory tract commonly observed in tobacco smokers
What are stimulants?
drugs that produce general increases in neural and behavioural activity
What is the substantia nigra?
the midbrain nucleus whose neurons project via the nigrostriatal pathway to the striatum of the basal ganglia; it is part of the mesotelencephalic dopamine system
What is a teratogen?
a drug or other chemical that causes birth defects
What is THC?
delta-9-tetrahydrocannabionol, the main psychoactive constituent of marijuana
What is the ventral tegmental area?
the midbrain nucleus of the mesotelencephalic dopamine system that is the major source of the mesocorticolimbic pathway
What is withdrawal syndrome?
the illness brought on by the elimination from the body of a drug on which the person is physically dependent
What are the advantages of oral route of administration of drugs?
Its ease and relative safety
What are the disadvantages of oral route of administration of drugs?
It is unpredictable (influenced by many factors)
What are the disadvantages of inhalation route of administration of drugs?
It is difficult to precisely regulate the dose and many substances can damage the lungs with chronic use
What is the type of drug tolerance that results from changes that reduce the amount of the drug gettin to its sites of action called?
Metabolic tolerance
What is the type of drug tolerance that results from changes that reduce the reactivity of the sites of action to the drug called?
Functional tolerance
What type of tolerance usually occurs in response to chronic use of psychoactive drugs?
Functional tolerance
What adaptive neural changes are caused by functional tolerance?
Reduction in the number of receptors
Decrease receptor-substrate affinity
Decrease the reaction of the cell when the drug binds to a receptor
What type of study is used to assess contigent drug tolerance?
Before-and-after design
True or False:
Drug users are more likely to overdose when they administer the drug in a new context
True
See conditioned drug tolerance
True or False:
Exteroceptive stimuli is more effective that interoceptive stimuli at eliciting conditioned drug tolerance
False
They are equally effective
What is the major psyhoactive ingredient in tobacco?
Nicotine
What receptors does nicotine act on?
Nicotinic cholinergic receptors
What type of drug is alcohol?
A depressant
What are the phases of alcohol withdrawal syndrome?
6-8 hours after: Anxiety, tremor, nausea and tachycardia
10-30 hours: Hyperactivity, insomnia and hallucinations
12-48 hours: Convulsive activity
3-5 days: Delirium tremors (DTs)
What are the symptoms of fetal alcohol syndrome?
Brain damage, intellectual disability, poor coordination, poor muscle tone, low birth weight, retarded growth and/or physical deformity
What is the only side-effect of marijuana use?
Tachycardia - a single, large dose can trigger heart attacks in susceptible individuals
What receptors does THC act on and where are they found?
CB1 and CB2 receptors
CB1 is the most prevalent GPLR in the brain
CB2 is found on the CNS and immune cells
Why are THC receptors found in the brain?
There is a class of endogenous cannabinoid neurotransmitters called endocannabinoids
What was the first endocannabinoid to be isolated?
Anandamide
What are the effects of a cocaine spree?
Sleeplessness, tremors, nausea, hyperthermia, and in rare cases, psychotic symptoms
What illicit drug is considered an empathogen?
MDMA
How do cocaine and its derivatives effect neurons?
It alters the activity of dopamine transporters by blocking the reuptake of dopamine into the presynaptic neuron, so the dopamine remains in the synapse
What is the long term effects of using stimulants?
Cognitive impairments, increased risk of Parkinson’s disease, heart abnormalities and decreased gray matter in their prefrontal cortex
What are the two classes of endogenous opioids?
Endorphins and enkephalins
What is the molecular difference between heroin and morphine and what does it allow for?
Heroin is morphine with two acetyl groups added, which increases its ability to penetrate the blood-brain barrier
True or False:
Heroin was not included in the Harrison Narcotics Act
True
The company that produced it claimed that it wasn’t addictive
When was heroin outlawed in the United States?
1924
How long after using opioids does the withdrawal syndrome start?
6 to 12 hours
What are the symptoms of opiod withdrawal syndrome?
Increased restlessness
Watering eyes, running nose, yawning and sweating
Fitful sleep that lasts several hours
Chills, shivering, profuse sweating, nausea, vomiting and diarrhea, tremor, dilated pupils and spasms
When are the symptoms of opioid withdrawal most severe?
Second or third day
How long does opiod withdrawal last?
Around 7 days
True or False:
There are no severe long-term side effect of opioid abuse
True
Constipation, pupil constriction, menstrual irregularity and decreased sex drive is as bad as it gets
Broken down products of the body’s chemical reactions are called
Metabolites
_______ is a states of decreased sensitivity to a drug that develops as a result of exposure to it
Drug tolerance
A graph of the magnitude of the effect of different doses of a drug is referred to as a _______
Dose-response curve
______ are hypothetical conditional physiological responses that are opposite to the effects of a drug
Conditioned compensatory responses
Psychoactive drugs that produce feelings of affection and compassion are called _______
Empathogens
______ stimuli arise from outside the body
Exteroceptive
________ is described as the phase of alcohol withdrawal syndrome characterised by hallucinations, delusions, disorientation, agitation, confusion and hyperthermia
Delirium tremors
Chronic alcohol consumption causes extensive scarring of the lover, also called _______
Cirrhosis
The offspring of mothers who consume substantial quantities of alcohol during pregnancy may develop ______
Fetal alcohol syndrome
_______ are drugs whose primary effect produces a general increase in neural and behavioural activity
Stimulants
Morphine and codeine are constituents of ______
Opium
______ is a semisynthetic opioid that penetrates the blood-brain barrier more effectively that morphine
Heroin
______ heroin users were among the first to legally receive heroin injections from a physician for a small fee
Swiss
True or False:
The most important factor in addiction is the drugs’ hedonic effects
True
Hedonic = pleasurable
Which brain system plays an important role in intracranial self-stimulation?
Mesotelencephalic dopamine system
The cell bodies of mesotelecephalic dopaminergic neurons are found where?
Substantia nigra and ventral tegmental area
The axons of mesotelecephalic dopaminergic neurons project to where?
Prefrontal cortex, limbic cortex, olfactory tubercle, amygdala, septum, dorsal striatum, and in particular, the nucleus accumbens
What is the path of neurons that compose the nigrostriatal pathway?
Cell body is found in the substantia nigra and axons project to the dorsal striatum
The degeneration of the nigrostriatal pathway is associated with which disease?
Parkinson’s disease
What is the path of neurons that compose the mesocorticolimbin pathway?
Cell body is found in the ventral tegmental area and axons project to various cortical and limbic sites
True or False:
Many of the brain sites at which self-stimulation occurs are part of the mesocorticolimbic pathway
True
True or False:
Intracranial self-stimulation is often associated with an icrease in GABA release in the mesocorticolimbic pathway
False
Intracranial self-stimulation is often associated with an icrease in dopamine release in the mesocorticolimbic pathway
True or False:
Dopamine agonists tend to increase intracranial self-stimulation, and dopamine antagonists tend to decrease it
True
True or False:
Lesions of the mesocorticolimbic pathway tend to disrupt intracranial self-stimulation
True
What two methods were used to measure the rewarding effects of drugs?
Drug self-administration paradigm
Conditioned place-preference paradigm
What occurs in the drug self-administration paradigm?
Nonhuman animals press a lever to inject drugs into themselves through implanted cannulas (thin tubes)
What occurs during the conditioned place-preference paradigm?
Nonhuman animals repeatedly receive a drug in one compartment of a two-compartment box. Then, the drug-free rat is placed in the box, and the proportion of time it spends in the drug compartment, as opposed to the equal-sized but distinctive control compartment
What is the main advantage of the conditioned place-preference paradigm?
Subjects are tested while they are drug-free, which means that the measure of the incentive value of the drug is not confounded by other effects the drug might have on behaviour
True or False:
Laboratory animals would not self-administer microinjections of addictive drugs directly into the nucleus accumbens
False
They would
True or False:
Microinjections of addictive drugs into the nucleus accumbens did not produce a conditioned place preference for the compartment in which they were administered
False
They did
True or False:
Lesions to either the nucleus accumbens or the ventral tegmental area blocked the self-administration of addicitve drugs into general circulation or the development of drug-associated conditioned place paradigm
True
True or False:
Both the self-administration of addictive drugs and the experience of natural reinforcers were found to be associated with elevated levels of extracellular dopamine in the nucleus accumbens
True
What are the three stages in the development of an addiction?
Initial drug taking
Habitual drug taking
Drug craving and repeated relapse
What factors have been shown to increase the likelihood of initial drug taking in rats?
Food restriction, social stress and environmental stress
What factors have been shown to decrease the likelihood of initial drug taking in rats?
Environmental enrichment, social interaction and access to nondrug reinforcers
The anticipated pleasure associated with an action is known as what?
Positive-incentive value
The amount of pleasure that is actually experienced due to an action is known as what?
Hedonic value
How does the striatum of drug-addicted individuals react to drugs and drug-associated cues compared to a non-addicted individual?
In addicted individuals, striatal control of drug taking is shifted from the nucleus accumbens (i.e. ventral striatum) to the dorsal striatum
What are the three main causes of relapse in addicted individuals?
Stress
Drug priming
Exposure to cues
What are the two major conclusions about the mechanisms of drug addiction drawn through research on the self-adminissteration of stimulants?
All addictive drugs activate the mesocorticolimbic pathway
Dopamine is important for the reinforcing properties of all addictive drugs
Although \_\_\_\_\_\_\_\_\_\_ is classified as a depressant, it has stimulant effects at low doses. Select one: a. Morphine b. Alcohol c. Amphetamine d. Tobacco
b. Alcohol
A problem faced by theories of drug conditioning is predicting;
Select one:
a. whether or not there is a conditional stimulus.
b. whether or not there is an unconditional stimulus.
c. who will become addicted.
d. the direction of conditioned effects.
d. the direction of conditioned effects.
A state of decreased sensitivity to a drug as a result of previous exposure to the drug is called; Select one: a. psychological dependence. b. drug sensitization. c. drug tolerance. d. physical dependence.
c. drug tolerance.
Many self-stimulation sites; Select one: a. contain serotonergic neurons. b. are part of the mesotelencephalic dopamine system. c. contain dopamine antagonists. d. are adrenergic.
b. are part of the mesotelencephalic dopamine system.
Psychoactive drugs are those that affect;
Select one:
a. behaviour.
b. the activity of the central nervous system.
c. subjective experience.
d. all of the above
d. all of the above
Recent research suggests that during the transition from initial drug taking to habitual drug taking.
Select one:
a. there are impairments in the function of prefrontal cortex.
b. the control of drug taking is shifted from the nucleus accumbens.
c. the control of drug taking is shifted to the dorsal striatum.
d. all of the above
d. all of the above
The anticipated pleasure associated with an action is its _____________, whereas the actual pleasure experienced is its_____________.
Select one:
a. anhedonia; positive incentive value
b. hedonic value; positive incentive value
c. positive incentive value; hedonic value
d. anhedonia; hedonic value
c. positive incentive value; hedonic value
Which drug is currently an alternative to methadone as a treatment for heroin addiction? Select one: a. Laudanum b. Anandamide c. Codeine d. Buprenorphine
d. Buprenorphine
Which of the following drugs in high doses produces a syndrome of psychotic behaviour that is similar to paranoid schizophrenia? Select one: a. Opium b. Heroin c. LSD d. Cocaine
d. Cocaine
