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Drugs & The Brain

Drugs & The Brain. 1. Cells in the Brain 2. Electrical Processing 3. Chemical processing 4. Drugs and the Brain. Neurons: receive, integrate, and transmit info. Neurons are Specialized for Communication. Nerve cells are powered by electrical impulses

jared-kinney
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Drugs & The Brain

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  1. Drugs & The Brain 1. Cells in the Brain 2. Electrical Processing 3. Chemical processing 4. Drugs and the Brain

  2. Neurons: receive, integrate, and transmit info

  3. Neurons are Specialized for Communication • Nerve cells are powered by electrical impulses • Communicate with other nerve cells through chemical signals • Three basic phases: • Reception: Chemical signals are received from neighboring neurons (Dendrites) • Integration: Incoming signals are assessed (Cell Body) • Transmission: Signals are passed on to other receiving neurons (Axon)

  4. Neuron Structure Dendrite: detects chemical signals from neighboring neurons Cell body (soma): collects and integrates information Axon: transmits electrical impulses Terminal buttons: end of an axon; contains neurotransmitter Synapse: supports chemical communication between neurons Synaptic cleft: narrow gap between terminal button (presynaptic membrane) and dendrite (postsynaptic membrane) of neighboring neuron Myelin sheath: encases and insulates axons

  5. Electrical Processing Neurons receive electrical signals from other neurons If signal is large enough, neuron generates Action Potential Sends signal down axon to next neurons

  6. Action Potential • Rapid reversal of electrical potential, triggered by input from other neurons • Na+ ions allowed in, causing inside to become positively charged • K+ ions flow out, Na/K Pump activated-ending signal • Action potential conducted down axon, to terminal

  7. Synaptic Transmission: Chemical Processing

  8. Electrical Signals into Chemical Signals

  9. Steps in Synaptic Transmission • Synapse: space between neurons • Vesicles: contain Neurotransmitter • Neurotransmitter released from terminal after arrival of action potential • Neurotransmitter binds to receptor • Opening of Receptors allows ion flow, influencing membrane potential

  10. Drugs and the Brain Drugs produce their effects by altering ongoing electrical or chemical processes

  11. Psychoactive drugs: Mind altering substances that change the brain’s neurochemistry (marijuana, cocaine, amphetamines, MDMA, opiates) • Drug effects: depends on which neurotransmitter system it activates

  12. Drugs alter Neurotransmitter effects • Agonists: enhance the actions of neurotransmitters • Antagonists: inhibit the actions of neurotransmitters

  13. Marijuana • Most widely used illicit drug • Not easily categorized as a stimulant, depressant, or hallucinogen • Produces a relaxed, contented mood, more vivid perceptions • Experienced users appreciate the effects more than novices (Kuhn, Swartzwelder, & Wilson, 2003) • Psychoactive ingredient: THC • Operates at cannabanoid receptors • Medical use is controversial

  14. Cocaine • Long history of use in the United States (Coca-Cola) • Stimulant • Users experience increased alertness, increased confidence and sociability • Increases dopamine levels at synapses • Habitual use of cocaine in large quantities can lead to paranoia, psychotic behavior, and violence (Ottieger, Tressell, Inciardi, & Rosales, 1992)

  15. Cocaine • Blocks Re-uptake of Dopamine at transporters • Prolongs effect of dopamine at receptor

  16. Amphetamines • Long history of use for weight loss, staying awake • Seldom used for legitimate medical purposes • Methamphetamine: World’s second most commonly used illicit drug • Increases dopamine production; blocks reuptake • Damages brain structures responsible for cognition, memory and emotion (Kim et al., 2006; Thompson et al., 2004) • Causes considerable physical damage

  17. MDMA • “Ecstasy” has gained in popularity since the “raves” of the 1990s • High school students’ use increased from 3.7% to 4.7% between 2009 and 2010 (National Institute of Drug Abuse, 2010) • Users feel energized and may hallucinate • Lowers dopamine; increases/depletes serotonin availability • May produce depression, memory loss, difficulty in completing complex tasks (Fischer et al., 1995; Kalechsteinet al., 2007)

  18. Hallucinogens & Serotonin • LSD and other hallucinogens are structurally similar to serotonin • Agonists at post-synaptic serotonin receptors

  19. Opiates • Used historically to relieve severe pain • Depressant • Heroin, morphine, codeine • Users experience analgesia, relaxation, euphoria • Highly addictive due to effects at opiate receptors (pleasure) and dopamine receptors (increased wanting of the drug) • Long-term use can lead to attention and memory problems (Gruber, Silveri, & Yurgelun-Todd, 2007)

  20. Aricept: blocks enzyme (acetylcholinesterase) that break down acetylcholine

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