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Psychology 3506 Neuropharmacology

Psychology 3506 Neuropharmacology. Dr. David R. Brodbeck. Introduction. What is a drug? Well, we all know what it means… That ain’t good enough, we need some sort of definition Alters physiology, but is not food….. Vitamin C? Some things are also poisons Gasoline, mugwart..

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Psychology 3506 Neuropharmacology

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  1. Psychology 3506Neuropharmacology Dr. David R. Brodbeck

  2. Introduction • What is a drug? • Well, we all know what it means… • That ain’t good enough, we need some sort of definition • Alters physiology, but is not food….. • Vitamin C? • Some things are also poisons • Gasoline, mugwart.. • Perhaps we don’t need a definition

  3. Still…. • What if you take it not to treat anything or to get high • Coke • Coffee • Beer • Frankly, an intuitive definition will have to do.

  4. Names • Chemical Names • 7-chloro-1,3-dihydro-1-methyl-5-phenyl-2H-1,4-benzodiazepin-2-one. • How very helpful…. • Generic Names • diazepam • flouexitine • Trade Names • Valium • Prozac

  5. Dosages • Different dosage sizes will have different effects on different people, animals. • Especially if they weigh different amounts • Standardize it • mg/kg

  6. Dose Response Curves • Pick some variable for a response • Plot response as a function of dose • One drink and I am relaxed • 4 drinks and I am tipsy • 8 drinks and I am ‘relaxed’ again. • This shape is very common in DRCs

  7. Dose Response Curves • Effect of morphine and morphine + naloxone on activity (left) and nosepoke (right) (Criswell, 1987)

  8. Describing Effectiveness • ED50 and LD50 • Effective dose for 50 percent of the population • subjective • Lethal dose for 50% of the population • Therapeutic Index (TI) • TI = LD50 / ED50 • Higher the index, the safer the drug

  9. Potency and Effectiveness or Efficacy • Find the ED50 for both drugs • The one with the lower ED50 is more potent • Efficacy is about the maximum amount of effect the drug will have • Morphine vs. aspirin

  10. Some other key terms • Primary effects or main effects vs. side effects • Depends on your point of view • If you are taking morphine to deal with pain, the main effect is the analgesia and the (albeit fun) side effect is being high • If you are taking it because you want to groove to Quicksilver Messenger Service….

  11. Key Terms, Continued • Agonists • Antagonists • Naloxone and opiates for example • Additive effects • Superadditive effects • Sleeping pills and martinis

  12. Routes of Administration • If you are injecting, you need a vehicle • Saline • Subcutaneous • Slowest absorption • Intramuscular • Intraperitoneal • Fastest absorption • Intravenous • intraventricular

  13. Routes… • Get into bloodstream via diffusion • (except IV injections obviously) • Inhalation works the same way • Gasses or solids • Orally, depends on lipid solubility • More soluble the easier the absorption • Ionized molecules are not absorbed • Rate is constant

  14. Distribution and Metabolism • Once absorbed, the drug has to get past the blood brain barrier • Get across the membrane through passive or active transport • Protein binding stops some • Taken out of blood stream by kidneys, liver • Measured in half life

  15. What affects metabolism? • Age • Sex • Species • Enzyme induction • Enzyme depression • Putting absorption and excretion together, you get the time course of the drug

  16. Therapeutic window • You want to maintain enough of the drug in the system • Easy if the drug has a long time course • Harder if the time course is longer

  17. So, there’s the pharmacology, what about the behaviour? • In behavioural pharmacology we use dose as the Independent variable and response (behaviour) ad the dependent variable • Need a control group or control condiiton • Between subjects designs • Within subjects designs • Statistical tests are done • Placebo controls are VERY IMPORTANT

  18. Importance of placebo controls • Levine, Gordon and Fields (1977) • 2 groups, one given real analgesic, other given placebo • Both report analgesia! • Naloxone given • Only return of pain in analgesia group

  19. I bet you could teach a course on research methods…. • Co relational research is also important • CORRELATION IS NOT CAUSATION • Science is not done in a vacuum • Unstructured observation is as useful as champagne in the Leafs dressing room • Can lead to ideas though • Systematic introspection is OK • Questionnaires like the MPQ

  20. Common Dependent Variables • Arousal level (use EEG) • Perceptual stuff • Flicker fusion • Thresholds • Timing • Cognitive stuff • Memory • vigilance

  21. More Measures • Motor tasks • Pursuit rotor • Tapping rate • Non humans too • Timing • Learning and memory • Avoidance • Paw lick test

  22. Conditioning • Drug effects can be conditioned • But, UR <> CR (not always anyway) • If drug affects PNS, you get the opposite effect!! • Behavioural Tolerance • Campbell and Sieden (1973) • Amphetamine and DRL

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