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Questions and Answers
The mesolimbic pathway is involved in reward, attention, and learning.
The mesolimbic pathway is involved in reward, attention, and learning.
True
LSD, a serotonin antagonist, causes hallucinations.
LSD, a serotonin antagonist, causes hallucinations.
False
Addictive drugs create an inappropriate learning signal that contributes to compulsive behavior.
Addictive drugs create an inappropriate learning signal that contributes to compulsive behavior.
True
The hypothalamus is responsible for emotional responses in the brain reward system.
The hypothalamus is responsible for emotional responses in the brain reward system.
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Initial drug use is always voluntary and does not lead to addiction.
Initial drug use is always voluntary and does not lead to addiction.
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Nicotine is an alkaloid found in the tobacco plant.
Nicotine is an alkaloid found in the tobacco plant.
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Cotinine is the primary metabolite of nicotine in humans.
Cotinine is the primary metabolite of nicotine in humans.
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Vaping has been proven to be completely safe for health.
Vaping has been proven to be completely safe for health.
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Smoking nicotine has no significant health complications.
Smoking nicotine has no significant health complications.
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Once addiction develops, brain changes can affect voluntary decision-making.
Once addiction develops, brain changes can affect voluntary decision-making.
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Nicotine acts as an antagonist at nicotinic acetylcholine receptors.
Nicotine acts as an antagonist at nicotinic acetylcholine receptors.
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Smoking and alcohol consumption can both alter gene expression.
Smoking and alcohol consumption can both alter gene expression.
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The pathophysiology of nicotine addiction is unrelated to brain circuitry.
The pathophysiology of nicotine addiction is unrelated to brain circuitry.
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Study Notes
Reward & Pleasure
- Nicotine, cocaine, and other drugs affect the reward pathway in the brain.
- Drugs block the dopamine transporter, preventing dopamine from being reabsorbed.
- This leads to an increase in dopamine in the synapse, intensifying the pleasurable sensation.
- The reward pathway is an important area in the brain for the development of drug addiction.
Lecture Objectives
- Students will learn about the role of neurotransmitters in feelings of pleasure and reward.
- Students will learn how the reward pathway contributes to drug addiction.
- Students will understand the psychosocial and medical complications of drug addiction.
Neuronal Cells
- Neurons communicate via electrical and chemical signals.
- Dopamine, a neurotransmitter, plays a critical role in reward pathways.
- Key parts of the neuron include dendrites, axon, terminal buttons, and synapse.
The Reward Pathway
- Dopamine transporter is blocked by cocaine.
- Dopamine receptor receives increased dopamine.
- Intensity of effect is amplified.
- The transmitting neuron, alongside the receiving neuron, are crucial in the process.
Brain Reward Regions
- Natural rewards (food, sex, social interactions) utilize the brain's reward circuitry.
- This circuitry is old from an evolutionary perspective.
- Drugs of abuse affect similar brain regions involved in reward.
- Highly integrated "limbic" circuits are innervated by dopamine neurons in the ventral tegmental area (VTA).
- The brain areas involved are: Nucleus accumbens, Prefrontal cortex, Amygdala, Hippocampus, and VTA.
Brain Reward System
- The mesolimbic pathway is associated with reward, attention, learning, and memory.
- The mesocortical pathway is associated with emotion and motor function.
- The hypothalamus is associated with motivated behaviors like food, sex, and social interactions.
Dopamine Hypothesis of Addiction
- Under normal conditions, the mesolimbic dopamine signal is a learning signal for adjusting behaviors.
- Addictive drugs produce a strong but inappropriate learning signal, leading to compulsive behavior.
Dopamine Pathways
- Reward (motivation), pleasure, euphoria, and fine motor functions are linked to dopamine.
- Compulsion and perseveration are also linked to dopamine.
Serotonin/5-HT
- Serotonin is also known as the "happy hormone."
- It plays a role in various physiological processes, including sleep, appetite, thermoregulation, and pain perception.
- Serotonin is associated with depression, obsessive-compulsive disorder (OCD), and anxiety.
Glutamate
- Glutamate is the primary excitatory neurotransmitter in the central nervous system (CNS).
- It plays a vital role in learning, memory, and brain plasticity.
- Glutamate is part of the reward pathway, and illicit drugs increase its transmission.
GABA
- GABA is the main inhibitory neurotransmitter in the brain.
- It plays a key role in anxiety and addiction regulation.
Different MoA of Drugs
- Drugs of abuse mimic neurotransmitters by activating receptors.
- Drugs can block the dopamine pump (cocaine), activate or inhibit ion channels (alcohol, PCP).
- This alters intracellular chemical messengers, causing long-lasting changes in the brain.
The Problem
- Drug addiction is considered a disease.
- Initial drug use may be voluntary; however, continued use can lead to neurological changes.
- Abuse drugs alter gene expression and brain circuitry.
- Addiction leads to an inability to make voluntary decisions, resulting in cravings and compulsive behavior.
Psychosocial Manifestations of Drug Abuse
- Psychological/Behavioral: agitation, irritability, dysphoria, difficulty coping, mood swings, hostility, violence, etc
- Family: chronic family dysfunction, marital problems, decline in school performance, anxiety and depression in family members, divorce.
- Social: alienation, loss of old friends, gravitation toward others with similar lifestyles.
Work/School
- Decline in performance, frequent job changes, frequent absences, requests for work excuses are common.
Legal
- Arrests for disturbing the peace, driving while intoxicated, stealing, or drug dealing are often seen.
Financial
- Borrowing or owing money, or selling possessions can be common.
Health Complications
- There are many potential health complications associated with drug abuse, affecting the reproductive system, cholesterol levels, lymph nodes, skin, breathing, the body in general (long-term effects), nose, and circulatory systems.
Nicotine Metabolism
- The most important metabolite of nicotine (in most mammals) is cotinine.
- In humans, roughly 70-80% of nicotine is converted to cotinine.
- Cotinine is an indicator of smoking or tobacco exposure.
Tobacco & Nicotine
- Nicotine, an alkaloid found in tobacco plants, is the major psychoactive component.
- Nicotine primarily acts as an agonist at nicotinic acetylcholine receptors.
Vape/E-Cig
- Vape devices produce an aerosol by heating liquid containing flavorings and chemicals.
- This liquid often contains nicotine, marijuana, or other drugs.
- Vaping is inhaled into the lungs then expelled.
Vape Statistics
- Data shows vaping prevalence, daily use, and nicotine use among current smokers.
Is Vape Safe?
- Vaping makers know it is addictive.
Genetic Association
- Genes like CYP2A6, OPRM1, HTR2A, and CHRNA4 impact a person's susceptibility to nicotine addiction.
Smoking Toxicity
- Smoking exposes the body to various toxic chemicals.
- These chemicals result in various health problems and complications.
Nicotine Toxicity
- Nicotine has significant cardiovascular, carcinogenic, and reproductive effects.
Homework
- Students should prepare for a mini debate on the safety of vaping.
- Students should review the material covered in the lesson.
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Description
Test your knowledge on the mesolimbic pathway, the role of nicotine and LSD in addiction, and the brain's reward system. This quiz explores key concepts related to drug use and its effects on behavior and decision-making.
