PSYC 2920 Lecture 8

1. PSYC 2920Lecture 8

2. Dependence, Addiction and theSelf-Administration of Drugs • Factors that Alter the Reinforcing Value of Drugs • Other Deprivations and Motivations • Hunger • 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

3. Dependence, Addiction and theSelf-Administration of Drugs • The Neuroanatomy of Motivation and Reinforcement • 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

4. Dependence, Addiction and theSelf-Administration of Drugs Motivation Control System of the Brain

5. Reward circuitry

6. Reward circuitry continued

7. Dependence, Addiction and theSelf-Administration of Drugs • The Neuroanatomy of Motivation and Reinforcement • “Wanting” Versus “Liking” in Reinforcement • “Pleasure Centers” • Reinforcing Effects of Drugs • Stress and Reinforcement • Stress, both present and in the past, increases the strength for reinforcing stimulus.

8. Dependence, Addiction and theSelf-Administration of Drugs • What Happens During Addiction? • Addiction • Drugs alter the functioning of the motivation system and the behavior. • How? • Theory

9. Dependence, Addiction and theSelf-Administration of Drugs • Incentive Sensitization Theory • Drug Craving • The desire to experience the effect(s) of a previously experienced psychoactive substance. • Robinson & Berridge • 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

10. Dependence, Addiction and theSelf-Administration of Drugs • Hedonic Dysregulation and Adaptation • 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 • Hedonic dysregulation • Dysphoria • Psychological withdrawal

11. Comparing incentive sensitization to Hedonic dysregulation (aka allostasis model) • Incentive sensitization • impulsivity • pure “psychological” addiction • cue-associated relapse • Positive reinforcement model • Hedonic dysregulation • Transition from impuslivity to compulsivity • Focus on withdrawal • Stress-related relapse • Negative reinforcement model

12. Dependence, Addiction and theSelf-Administration of Drugs • Behavioral Economics: Choosing to Use Drugs • 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. • Spiral to Addiction • Confound for withdrawal-based explanations?

13. Dependence, Addiction and theSelf-Administration of Drugs • Behavioral Economics: Choosing to Use Drugs • Choice and Time • Discounting of delay • Perceived value of something decreases the further away it is in time

14. Dependence, Addiction and theSelf-Administration of Drugs • Behavioral Economics: Price and Demand • Inelastic • Consumers continue to spend the same amount or more for a drug even though they are not able to purchase as much. • Elastic • Consumers start spending less for the drug in response to a price increase.

15. Dependence, Addiction and theSelf-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).