Biopsychology Exam 4-PART 4

Biopsychology Exam 4-PART 4 - Biopsychology Exam 4 Lecture...

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Biopsychology Exam 4 Lecture 21- Drug Abuse Opiate use o OPIATE: derived from opium plants; used in pain medicine MORPHINE : initially the most popular pain medication; named after god Mopheus (god of dreams); schedule II narcotic in U.S. “the soldiers disease”- post civil war morphine dependence (when a person was shot, they would give them opium to help the pain. .if they survived they became addicts) Over 90% of world opium was in china in late 1800s (over 25% of the adult population became dependent) now over 90% of world’s opium in Afganistan (10’s of billions of dollars go to the population—supports over 200,00 families) “the soldiers disease”- post civil war morphine dependence (when a person was shot, they would give them opium to help the pain. .if they survived they became addicts) HEROIN : schedule I narcotic in U.S. (illegal since 1924; legally prescribed in England); most harmful abused drug Initially marked less addictive than morphine, but is largely metabolized into morphine o OPIOID ABUSE: abuse of prescription opioids=major problem (it is common for people to become dependent) STIMULANT (low doses) and DEPRESSIVE EFFECTS (high does) Direct injection of opioid into VTA causes robust stimulant effect , but at high doeses stimulant effects are masked (reducing behavioral activation) When drug leaves system, animal experiences WITHDRAWAL (symptoms are opposite of acute effect (positive symptoms)) When people have been taking drugs for a while and then the drugs are taken away Iritablitily, discomfort, disphoria, etc. The role of nucleus accumbens o All abused drugs (no just opiates) INCREASE DOPAMINE SIGNALING in NAc
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COCAINE=increases dopamine signaling preferentially in NAc shell [*much greater increase in shell] Tests of drug abuse in lab o Rats self-administered heronin (.1) for first 6 days by pushing a bar; then dose was cut in half for last 6 days, so rats DOUBLED the number of lever presses they did to get more infusion of the lower dose (to make sure they got the “desired” drug amount) rats were able to tell how much drugs they were getting and able to adjust doses to reach homeostatic state o MICRODIALYSIS: used to sample the neurochemical environment in specific brain regions following drug infusions DOPAMINE (or other molecules) diffuses through dialysis membrane and samples are collected (every 10 mins) and measure its HPLC ***MICRODIALYSIS LED TO UNDERSTANDING THAT DRUGS OF ABUSE INCREASE DOPAMINE RELEASE IN NAc Many microdialysis studies done to see how drugs alter dopamine signaling in different striatal subregions [low morphine dose to high dose=INCREASE in NAc shell (no increase in core)] o **FAST-SCAN CYCLIC VOLTAMMETRY= fasted (measures dopamine 10 times per second!); utilizes micro electrodes made from a single strand of carbon fiber (fibers lowered directly into the brain) measures change in dopamine concentration (difference in shell is
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This note was uploaded on 02/18/2011 for the course PSYCH 230 taught by Professor Unkown during the Winter '08 term at University of Michigan.

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Biopsychology Exam 4-PART 4 - Biopsychology Exam 4 Lecture...

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