PSYC 2920
Lecture 8
Dependence, Addiction and the
Self-Administration of Drugs
Factors that Alter the Reinforcing Value of
Drugs
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Other Deprivations and Motivations
Hunger
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Previous Experience with Other Drugs
Previous Experience with the Same Drug
Physical Dependence
Priming
Conditioned Reinforcement
Second-Order Schedules
Conditional tolerance
drug seeking vs. taking have dissociable mechanisms
Dependence, Addiction and the
Self-Administration of Drugs
The Neuroanatomy of Motivation and
Reinforcement
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Olds and Milner (1954) Experiment
Reinforcement Centers
Motivation Control System of the Brain
Ventral tegmental area (VTA)
Nucleus accumbens
Mesolimbic dopamine system
Basal ganglia
Motor loop
Thalamus > cortex > amygdala > hippocampus
Learning and memory system
Incentive salience
Dependence, Addiction and the
Self-Administration of Drugs
Motivation Control System of the Brain
Reward circuitry
Reward circuitry continued
Dependence, Addiction and the
Self-Administration of Drugs
The Neuroanatomy of Motivation and
Reinforcement
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“Wanting” Versus “Liking” in Reinforcement
“Pleasure Centers”
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Reinforcing Effects of Drugs
Stress and Reinforcement
Stress, both present and in the past, increases the strength
for reinforcing stimulus.
Dependence, Addiction and the
Self-Administration of Drugs
What Happens During Addiction?
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Addiction
Drugs alter the functioning of the motivation
system and the behavior.
How?
Theory
Dependence, Addiction and the
Self-Administration of Drugs
Incentive Sensitization Theory
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Drug Craving
The desire to experience the effect(s) of a previously
experienced psychoactive substance.
Robinson & Berridge
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Motivational aspect (“wanting”) is sensitized while
(“liking”) shows tolerance
Provides a good explanation strong craving in the
absence of dysphoric withdrawal.
Provides an explanation for impulsivity
Dependence, Addiction and the
Self-Administration of Drugs
Hedonic Dysregulation and Adaptation
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Based on physical dependence model
Allostatic process
Repeated use and/or cessation of use leads to
dysphoria, anxiety, depression
Set points change if drug use is persistent
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Hedonic dysregulation
Dysphoria
Psychological withdrawal
Comparing incentive sensitization to
Hedonic dysregulation (aka allostasis
model)
Incentive sensitization
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impulsivity
pure “psychological” addiction
cue-associated relapse
Positive reinforcement model
Hedonic dysregulation
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Transition from impuslivity to compulsivity
Focus on withdrawal
Stress-related relapse
Negative reinforcement model
Dependence, Addiction and the
Self-Administration of Drugs
Behavioral Economics: Choosing to Use
Drugs
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Based on behavioral mechanisms of positive
reinforcement
Making choices
The Matching Law
Animals distribute their resources (time, money,
and effort) to different responses in proportion to
the density of reinforcement provided by the
response.
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Spiral to Addiction
Confound for withdrawal-based explanations?
Dependence, Addiction and the
Self-Administration of Drugs
Behavioral Economics: Choosing to Use
Drugs
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Choice and Time
Discounting of delay
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Perceived value of something decreases the further
away it is in time
Dependence, Addiction and the
Self-Administration of Drugs
Behavioral Economics: Price and
Demand
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Inelastic
Consumers continue to spend the same amount or
more for a drug even though they are not able to
purchase as much.
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Elastic
Consumers start spending less for the drug in
response to a price increase.
Dependence, Addiction and the
Self-Administration of Drugs
Behavioral Economics:
Price and Demand
• Demand curves for monkeys
responding on FR schedules
of 4, 8, 16, 32, 64, and 128 to
receive access to a drinking
tube that delivered water
containing phencyclidine
(PCP).