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Chapter 14 Manipulating the Brain
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Electrical Activity in the Brain
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Electrical Activity at the Cellular Level + _ + _ + _ _
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Balance There are many neurotransmitters Some excite (depolarize) Some inhibit (hyperpolarize) Some go both ways (depending on the receiving cell) A balance of excitation and inhibition
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Drugs Alter balance Beyond the limits of excitation is seizure Beyond the limits of inhibition is respiratory failure, cardiovascular collapse and death
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General Depressants Ethyl alcohol (the kind you drink, all others are poison) Barbiturates Anesthetics
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General Depressants Depress electrical activity Disrupt membranes and increase action of GABA (an inhibitory neurotransmitter) All electrically excitable cells are effected –Nerves –Muscles (heart, skeletal, smooth) –Kidney
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Inhibition is more sensitive than excitation
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Barbiturates Sedatives and hypnotics Non-selective general depression of electrical activity Barbituric acid, pentobarbital, seconal, pentothal- How long they last
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Barbiturate Uses Epilepsy – many types Sleeping pills Side effects –Tolerance- The more you take, the more you need to take to have the same effect –Dependence- Adverse reaction to withdrawal
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Barbiturates – Other Side Effects Liver – increased metabolism of –Barbiturates –Steroids –Fat soluble vitamins
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Ethyl Alcohol The kind you drink Brain Liver Cardiovascular Digestion
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Selective depression of electrical activity in the brain Manipulation of specific neurotransmitter systems Increase inhibition Decrease excitation
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Benzodiazepines Aka. Librium, Valium Increase the effect of GABA on the receiving cell Inhibition within a level –Reticular formation –Hypothalamus –Limbic system –Cerebral cortex
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Benzodiazepines: Uses Sleeping pills Less depression of medullary centers than barbiturates Some types of epilepsies Parkinson’s disease Anti-anxiety
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Benzodiazepines: Side Effects Drowsiness, fatigue, loss of co-ordination, dizziness, blurred vision, behavioral With alcohol – lethal Tolerance Dependence
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Neurotransmitters: Excitation and Inhibition
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Food Additives MSG (monosodium glutamate) Aspartame –40% aspartic acid –50% phenylalanine –10% methanol
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Glycine Strychnine – glycine antagonist Exciting - even to seizures
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Mixed Neurotransmitters Sometimes excitatory, sometimes inhibitory Depends on receiving cell Biogenic amines
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Synthesis of Biogenic Amines Neurotransmitters Phenylketonuria (PKU)
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Biogenic Amines Adrenalin/noradrenalin –Stress Responses –Reward –Arousal –Mood Dopamine Motor control Social behavior Hypothalamic releasing factors
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Serotonin AKA – 5-hydroxytryptamine Lining of digestive system Platelets Brain –Mood –Drives –Thinking and perception –Sleep and attention –Hypothalamus
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Mechanism of Transmission
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Many Drugs Cross-reactivity between receptors Subtypes of receptors Drugs –Antagonists –Agonists –Block destruction –Block re-uptake –Cause release
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“Speeds” Amphetamine and derivatives Cocaine Both cause release and block re-uptake Acute stress response Euphoria, paranoia Extreme focus of attention Seizures
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“Speed” Uses Attention deficit disorder (ADD) Diet Pills Recreation
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Speed and the Sympathetic Nervous System
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Depression What is it? Unipolar Bipolar (manic – depression cycling)
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Antidepressants Hypothesis: depression is caused by depletion of one or more of the biogenic amines in the limbic system
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Tricyclic Antidepressants Blocks recovery of noradrenalin and serotonin Causes build-up of both Interferes with both sympathetic and parasympathetic control
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Monoamine Oxidase Inhibitors Block the enzymes that break down monoamines Biogenic amines build up in nerves and leak out Monoamines are in many places the besides brain…also in foods
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Prozac and Paxil Blocks the reuptake of serotonin which causes build up Adverse effects –Headache –Nausea –Dry mouth –Dizziness, tremors –Sexual dysfunction Hallucinations, aggression (LSD)????????????
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Lithium Li + …….Na + Limited range between efficacy and toxicity Kidney toxicity
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Mental Disorders Psychosis Schizophrenia Hypothesis: serotonin deficiency in limbic system Psychotomimetic drugs (LSD) Dopamine excess???? Parkinson’s disease
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Drugs Phenothiazines –Block dopamine and other biogenic amines –Even out behavior, sedation –Muscle tremors –Lots of problems but makes person tractable
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Epilepsy Uncontrolled electrical activity in the brain Benzodiazopines, barbiturates Phenytoin (dilantin), Valproate – Na + channel blocker Ca ++ channel blockers
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Xanthines Blocks the breakdown of the second messenger cAMP Caffeine, theobromine - food Theophylline - drug
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Nicotine Stimulates sympathetic response Attention Drug seeking behavior
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Cannabinoids (AKA: marijuana) Mixture of compounds >Cannabinoid receptors: two types Immune Nervous system >endocannabinoids – anandamide (synthesized from arachidonic acid) >synthetic (pharmacological)
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Cannabinoids cont. >Psychoactive (general feeling of well-being, heighten awareness of sound and sight) most active psychotrophic: delta-9– tetrahydrocannabinol >Immune system: anti-inflammatory >Nervous system: AIDs and cancer: decrease nausea, increase hunger Glaucoma: decrease intraocular pressure chronic pain: decrease perception
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Balance Drugs alter the balances of the brain
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