PSYC 2920PSYC 2920

Lecture 8Lecture 8

Dependence, Addiction and theDependence, Addiction and theSelf-Administration of DrugsSelf-Administration of Drugs

Factors that Alter the Reinforcing Value of Factors that Alter the Reinforcing Value of DrugsDrugs Other Deprivations and MotivationsOther Deprivations and Motivations

HungerHunger Previous Experience with Other DrugsPrevious Experience with Other Drugs Previous Experience with the Same DrugPrevious Experience with the Same Drug Physical DependencePhysical Dependence PrimingPriming Conditioned ReinforcementConditioned Reinforcement Second-Order SchedulesSecond-Order Schedules

Conditional toleranceConditional tolerancedrug seeking vs. taking have dissociable mechanismsdrug seeking vs. taking have dissociable mechanisms

Dependence, Addiction and theDependence, Addiction and theSelf-Administration of DrugsSelf-Administration of Drugs

The Neuroanatomy of Motivation and The Neuroanatomy of Motivation and ReinforcementReinforcement Olds and Milner (1954) ExperimentOlds and Milner (1954) Experiment

Reinforcement CentersReinforcement Centers Motivation Control System of the BrainMotivation Control System of the Brain

Ventral tegmental area (VTA)Ventral tegmental area (VTA)

Nucleus accumbensNucleus accumbens

Mesolimbic dopamine systemMesolimbic dopamine system

Basal gangliaBasal ganglia

Motor loopMotor loop

Thalamus > cortex > amygdala > hippocampusThalamus > cortex > amygdala > hippocampus

Learning and memory systemLearning and memory system

Incentive salienceIncentive salience

Dependence, Addiction and theDependence, Addiction and theSelf-Administration of DrugsSelf-Administration of Drugs

Motivation Control System of the BrainMotivation Control System of the Brain

Reward circuitryReward circuitry

Reward circuitry continuedReward circuitry continued

Dependence, Addiction and theDependence, Addiction and theSelf-Administration of DrugsSelf-Administration of Drugs

The Neuroanatomy of Motivation and The Neuroanatomy of Motivation and ReinforcementReinforcement ““Wanting” Versus “Liking” in ReinforcementWanting” Versus “Liking” in Reinforcement

““Pleasure Centers”Pleasure Centers” Reinforcing Effects of DrugsReinforcing Effects of Drugs Stress and ReinforcementStress and Reinforcement

Stress, both present and in the past, increases the strength Stress, both present and in the past, increases the strength for reinforcing stimulus.for reinforcing stimulus.

Dependence, Addiction and theDependence, Addiction and theSelf-Administration of DrugsSelf-Administration of Drugs

What Happens During Addiction?What Happens During Addiction? AddictionAddiction

Drugs alter the functioning of the motivation Drugs alter the functioning of the motivation system and the behavior.system and the behavior.

How?How?

TheoryTheory

Dependence, Addiction and theDependence, Addiction and theSelf-Administration of DrugsSelf-Administration of Drugs

Incentive Sensitization TheoryIncentive Sensitization Theory Drug CravingDrug Craving

The desire to experience the effect(s) of a previously The desire to experience the effect(s) of a previously experienced psychoactive substance.experienced psychoactive substance.Robinson & BerridgeRobinson & Berridge

Motivational aspect (“wanting”) is sensitized while Motivational aspect (“wanting”) is sensitized while (“liking”) shows tolerance(“liking”) shows tolerance

Provides a good explanation strong craving in the Provides a good explanation strong craving in the absence of dysphoric withdrawal.absence of dysphoric withdrawal.

Provides an explanation for impulsivityProvides an explanation for impulsivity

Dependence, Addiction and theDependence, Addiction and theSelf-Administration of DrugsSelf-Administration of Drugs

Hedonic Dysregulation and AdaptationHedonic Dysregulation and Adaptation Based on physical dependence modelBased on physical dependence model Allostatic processAllostatic process

Repeated use and/or cessation of use leads to Repeated use and/or cessation of use leads to dysphoria, anxiety, depressiondysphoria, anxiety, depression

Set points change if drug use is persistentSet points change if drug use is persistent Hedonic dysregulationHedonic dysregulation

DysphoriaDysphoria

Psychological withdrawalPsychological withdrawal

Comparing incentive sensitization to Comparing incentive sensitization to Hedonic dysregulation (aka allostasis Hedonic dysregulation (aka allostasis

model)model) Incentive sensitizationIncentive sensitization impulsivityimpulsivity pure “psychological” addictionpure “psychological” addiction cue-associated relapsecue-associated relapse Positive reinforcement modelPositive reinforcement model

Hedonic dysregulationHedonic dysregulation Transition from impuslivity to compulsivityTransition from impuslivity to compulsivity Focus on withdrawalFocus on withdrawal Stress-related relapseStress-related relapse Negative reinforcement modelNegative reinforcement model

Dependence, Addiction and theDependence, Addiction and theSelf-Administration of DrugsSelf-Administration of Drugs

Behavioral Economics: Choosing to Use Behavioral Economics: Choosing to Use DrugsDrugs Based on behavioral mechanisms of positive Based on behavioral mechanisms of positive

reinforcementreinforcement Making choicesMaking choices The Matching LawThe Matching Law

Animals distribute their resources (time, money, Animals distribute their resources (time, money, and effort) to different responses in proportion to and effort) to different responses in proportion to the density of reinforcement provided by the the density of reinforcement provided by the response.response.

Spiral to AddictionSpiral to AddictionConfound for withdrawal-based explanations?Confound for withdrawal-based explanations?

Dependence, Addiction and theDependence, Addiction and theSelf-Administration of DrugsSelf-Administration of Drugs

Behavioral Economics: Choosing to Use Behavioral Economics: Choosing to Use DrugsDrugs Choice and TimeChoice and Time

Discounting of delayDiscounting of delay Perceived value of something decreases the further Perceived value of something decreases the further

away it is in timeaway it is in time

Dependence, Addiction and theDependence, Addiction and theSelf-Administration of DrugsSelf-Administration of Drugs

Behavioral Economics: Price and Behavioral Economics: Price and DemandDemand InelasticInelastic

Consumers continue to spend the same amount or Consumers continue to spend the same amount or more for a drug even though they are not able to more for a drug even though they are not able to purchase as much.purchase as much.

ElasticElasticConsumers start spending less for the drug in Consumers start spending less for the drug in response to a price increase.response to a price increase.

Dependence, Addiction and theDependence, Addiction and theSelf-Administration of DrugsSelf-Administration of Drugs

Behavioral Economics:Behavioral Economics:

Price and DemandPrice and Demand

• Demand curves for monkeys Demand curves for monkeys responding on FR schedules responding on FR schedules of 4, 8, 16, 32, 64, and 128 to of 4, 8, 16, 32, 64, and 128 to receive access to a drinking receive access to a drinking tube that delivered water tube that delivered water containing phencyclidine containing phencyclidine (PCP).(PCP).