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Chapter 18

PSYC 211 Chapter Notes - Chapter 18: Gaba Receptor, Putamen, Mesolimbic Pathway

Course Code
PSYC 211
Yogita Chudasama

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Chapter 18: Drug Abuse
Notes taken by: Ashley Brown
Contact for mistakes: Ashley.brown@mail.mcgill.ca
Common Features of Addiction
Even though drugs cause bad things, people continue to use them because they stimulate
brain mechanisms responsible for positive reinforcement. Their immediate effects are
more powerful than the realization that in the long term, bad things will happen.
Alcohol car accidents, fetal alcohol syndrome, Korsakoff’s syndrome, heart
disease, intracerebral hemorrhage
Smoking Lung cancer, heart attack, stroke, less healthy babies, babies with smaller
Cocaine psychotic behaviour, brain damage, death by overdose, competition for
lucrative and illegal markets, causes violent deaths.
A Little Background
Found substances in nature that had medicinal qualities. Also discovered recreational
ones that produced pleasurable effects when consumed
Addictive drugs and their site of action:
- ethyl alcohol NMDA receptor (indirect antagonist), GABAA receptor
(indirect agonist)
- Barbiturates GABAA receptor (indirect agonist)
- Benzodiazepines (tranquilizers) GABAA receptor (indirect agonist)
- Cannabis (marijuana) CB1 cannabinoid receptor (agonist)
- Nicotine Nicotinic ACh receptor (agonist)
- Opiates (heroin, morphine, etc.) μ and δ opiate receptor agonist
- Phencyclidine (PCP) and ketamine NMDA receptor (indirect antagonist)
- Cocaine blocks reuptake of dopamine (and serotonin and norepinephrine)
- Amphetamine causes release of dopamine (by running dopamine transporters
in reverse)
Positive Reinforcement
Positive reinforcement refers to the effect that certain stimuli have on the behaviours that
preceded them increases the frequency of behaviour
- immediate and powerful
Role in Drug Abuse
Effectiveness of a reinforcing stimulus is greatest if it occurs immediately after a
response occurs
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