7. Drug Use, Addiction and the Brains Reward Circuits Flashcards
What is tolerance?
the more you take a drug, the same drug will have less of an effect
What is withdrawal?
a syndrome in which when you stop taking a drug you have symptoms
What is sensitisation?
the more of a drug you take, the more effect you experience
- opposite of tolerance
What is conditioned drug tolerance?
- maximal tolerance effects are seen in the environment where the drug is usually administered
- therefore there is lower tolerance in other environments
- conditioned as you are responding to environmental cues
What is contingent drug tolerance?
- tolerance only develops to drug effects that are experienced
Explain what happens when a drug is administered orally
- easy but slow
- relatively safe
- absorption via digestive tract is unpredictable
What are the types of administration that happens via an injection?
- subcutaneously: under skin
- intramuscularly: into large muscles
- intravenously: into veins, delivered directly to brain
Explain what happens when a drug is administered via inhalation
- absorbed through capillaries in the lungs
Does the route of drug administration affect its addictive properties?
yes
- the faster it is absorbed, the more addictive the drug is
- therefore injecting is the most addictive, with smoking as an exception
- delay makes you less likely to learn (conditioning)
How does nicotine work?
binds to nicotinic acetylcholine receptors
- receptor named after the drug that binds to i
How do cocaine and amphetamine work?
- they are stimulants: block the the reuptake of dopamine, therefore more is left in the synapse
How does MDMA work?
- ecstasy blocks reuptake of serotonin and also reverses the reuptake transporter
- this leaves lots of serotonin in the synapse
Describe opiates
- heroin and morphine
- obtained from opium poppy
- have medical uses such as painkillers and treatment of cough and diarrhea
- bind to opioid receptors
How can we use self report to investigate drug use?
use a questionnaire that asks about drug use then devises a behaviour
Why do opiates stop pain?
they activate pain blocking neurons in the spinal cord
How can we use behavioural preference tests to investigate drug use?
- rat receives a drug in one out of two distinctive compartments
- then, the tendency of the rat to prefer the drug compartment (now drug free) is assessed
How can we use intra-cranial self stimulation to investigate drug use?
- rat will press the lever to receive direct stimulation of the brain
- if the rat presses the lever for drugs instead, it may stimulate the same regions of the brain
How can we use self-administration paradigm to investigate drug use?
- rat presses the lever to self inject a drug either into an area of its brain or into general circulation
- which lever it presses is assessed
How can the brain-reward system explain why people take drugs?
- fMRI scans show dopaminergic brain regions become activated when taking a drug
