lecture 16 LOs Flashcards
reinstatement paradigm for relapse in animal models
- train rats to administer drug (cues can be presented with drug infusion)
- take rat through extinction (lever press no longer delivers drug or cue, rat stops pressing)
- on test day no drug is provided but reinstatement of lever pressing can be induced by a drug prime, or a stressor, or a drug associated cue
what can a drug taste, drug related cue, or stress do to lever pressing
it can increase it in the absence of drug administration
what brain areas are the ability of the triggers (stressor, drug taste, drug associated cue) mediated by in the DA system
PFC, accumbens, amygdala
how do addictive drugs affect mesolimbic DA levels
dramatically increase the DA levels
DA doesnt mediate pleasure, but it does play a major role in wanting
what do drug induced increases in DA do to your brain
trick it into thinking that smth important is happening so it starts making associations with the environmental cues linked w drug taking
what does reward associated cues increasing DA release into the accumbens do
triggers the same behaviours that got you the rewards in the first place (aka drug seeking)
what can prolonged drug use do to the brain
induce a hyperactive (or sensitized) DA system
increased DA transmission can amplify the effects that drug-related cues exert over behaviour
what is the DA and addiction incentive sensitization hypothesis
cues associated with drug taking take control over behaviour
initial drug taking driven by pleasurable drug effects
over time tlerance develops to hedonic effects (you start to like the drug less)
however, effects on the DA system and the learning about drug related cues becomes sensitized
what happens to the associative memories between the drugs effect and their related cues in a hyperdopaminergic state
amplification
drug cues trigger more craving and then more drug taking, even if the effects of the drug aren’t as pleasurable
what is DA sensitization w repeated drug use
repeated drug use makes the DA system more responsive to drug related cues and stress
this results in changes in neural networks (rather than just DA neurons) that include the VTA, PFC, and the NAc
enhanced DA is thought to promote craving and drug seeking behaviours in response to triggers (like stress or drug related cues)
what would within system adaptations of neuroadaptations with repeated drug use result in
down regulation of reward circuitry (tolerance to pleasurabe affects of drugs)
what would between system adaptations and gradual recruitment of the anti reward system do in neuroadaptations with repeated drug use
stress and adversion related circuits that include NE, peptide transmitters, and dynorphin, the central nuecles of the amygdala and the NAc
what is physical withdrawal
can contribute to drug cravings and maintenance of addiction, it cannot explain all aspects of the behaviour though
initially what circuit do drugs activate
reward circuit promoting drugs positive reinforcing effects
after repeated drug use what happens to drugs ability to activate the reward circuitry
drugs become less effective at it