Exam 4 Flashcards
Addiction is a progressive behavorial syndrome characterized by _____ and ____ drug-seeking and consumption.
compulsive and out of control
Addiction is/isn’t curable and to determine effective treatment, we need to understand ________ and _________.
is not
physiology and pathology of motivated behaviors
Reward vs. Reinforcing (drugs do both)
Reward– a stimulus that is interpreted by the brain as intrinsically positive, or something that should be approached. (brain likes it)
Reinforcing– an increase in the probability of the occurence of a behavior that is paired (brain wants it)
________ is an experimental setup used to assess drug reward. How does it work?
conditioned place preference
Animals learn to associate one environment with passive drug adminsstration, and they will spend more time in the context in which they received the drug. (form of pavlovian conditioning
_________ is an experimental setup used to assess drug reinforncement. How does it work?
drug self-administration
Getting the drug is contingent on a specific behavior (lever-pressing)
The drug is interpreted as a reinforcer if it increases the occurrence of lever pressing.
The drug-induced _________ may be an important ______ for initial drug use in humans.
euphoria
reinforcing drive
Three central dopaminergic pathways
1) Nigrostriatal system:
SNc –> Striatum (putamen, caudate nucleus)
2) Mesolimbic system:
VTA –> NAc
3) Mesocortical:
VTA -> PFC
The nigrostriatal dopaminergic pathway is responsible for ______, but the _______ and ___ constitute the endogenous reward pathway
initiation of voluntary movement
mesolimbic and mesocortical
the mesocortical and mesolimbic systems are thought to be responsible for (2)
perception of reward
positive reinforcement
Dopamine produces overall inhibition of _____ in the _____ via activation of postsynaptic _____ receptors
GABAergic projection neurons
NAc
D2 (which is Gi coupled)
____________ allows for the identification of brain regions involved in reinforcement
intracranial self-stimulation
lever press leads to electrical stimulation of brain region
Stimulation of this region contains, which contains__________ elicits strongest reinforcement of self-stimulation behavior
medial forebrain bundle
mesocorticolimbic dopaminergic fibers
How do cocaine and amphetamine increase monoaminergic transmission
Cocaine inhibits monoamine transporter
Amphetamine induces reverse transport of monoamines
______________________ dramatically reduces the reinforcing effects of psychostimulants
Blockade of dopaminergic transmission in NAc (by administration of dopamine antagonists or dopaminergic neurotoxin)
The three types (name them) of opioid receptors are ____-coupled
mu, kappa, and delta
Gi
Action of opiates (2 mechanisms)
1) disinbition of VTA dopamine neurons via mu activation in GABAergic neurons, resulting in dopamine in NAc
2) dopamine-independent actions on mu and delta receptors, leading it inhibition of NAc projection neurons leading to reinforcement
___ and ___ receptors mediate the reinforcing effects of opiates, but ____ receptors cause _______, thus mediating aversion to opiates
mu and delta
kappa, reduction in dopamine release mediating aversive effects
Naltrexone, a ____________ reduces ethanol self-administration in animals
opioid receptor antagonist
Three actions of ethanol
1) directly activates VTA dopamine neurons, which
2) may inhibit GABA release onto dopamine neurons
3) induces relase of endogenous opioids in VTA or NAc
Two actions of nicotine
1) activates VTA dopamine neurons via nicotinic ACh
2) induce release of endogenous opioids
Three types of long-term changes in addiction course:
1) Compensatory adaptations in the brain regions that control somatic function (locus coeruleus)- days to two weeks
2) Adaptations in reward circuit (several weeks to lifetime)
3) Production of memories realated to drug use
LC compensatory adaptation is produced by _______ and ____ but not _____
opiates, alcohol
psychostimulants
Three adaptations in the brain reward circuit
1) tolerance— decrease in reinforcing effects of a drug which leads to a higher dosage
2) dependence– demad for drug to avoid emotional and physical withdrawal
3) sensitization– an increase in rewarding effexcts of a drg, which leads to more cravings and maybe psychostimulant psychosis
______ expose leads to ____, ____ while ____ exposure leads to ______
continuous– tolerance and dependence
intermittent– sensitization
Cue-induced relapse (examples)
1) relapse of withdrawal symptom if you visit the ste where you used drugs
The therapeutic actions of antidepressants and antipsychotics are dependent on ___________
time dependent adaptive changes in their respective brian regions
THe LC, the major ___________ nucleus, is responsible for three tings
noradrenergic
arousal, autonomic tone, and attention
LC activity is ______ by opiates via _________________
inhibited
activation of mu opioid receptors
How does continuous opioid use lead to tolerance? Dependence?
Tolerance– depressed firing in LC neurons gradually returns to normal after repeated opiate use
Dependence– administration of opioid antagonists causes a huge increase in LC fiting rates
_____________ is both necessary and sufficient to produce physical withdrawal symptoms
overactivation of LC neurons
Two mechanisms of how opiates inhibit LC neurons
1) activation of a certain type of K+ channel vira direct binding of Gi/o ro channel
2) inhibition of Na+ permeable channel via suppression of AC/cAMP cascade