The Cognitive Neuroscience of Addiction Flashcards
What is an addiction?
Intense cravings for desired substance and severe withdrawals when taken away
What is the effect of cocaine?
Reduced volume of frontal lobe, strokes and seizures
What is the effect of heroin?
Grey matter reduction, brain hypoxia, cerebral edema, stroke etc
What is alcoholism closely linked to?
Wernicke-Korsakoff syndrome
What is Wernicke-Korsakoff syndrome?
End stage of general brain shrinkage, characterised by anterograde amnesia (general forgetting)
What is the greatest cause of addiction?
Individual variability in susceptibility to addiction
What do associative learning theories of addiction say it is?
Conditioning
How does relapse take place?
Re-exposure to the cue (smoking) after attempted extinction procedures
How was the conditioned compensatory response investigated?
- Dogs injected with adrenaline
- HR increased
- Researchers noticed the HR increase was getting smaller after each injection
- Tolerance increasing
What else did they find out about the CCR?
Actual drug not needed
How can conditioning g show drug addiction?
UCS (HR increase - adrenaline) + CS (Contextual cues e.g. syringe) –> UR (Reduced HR)
CS (Cues) –> CR (Reduced HR)
How can heroin and a CCR lead to an overdose?
- Reduced HR from heroin, organism compensated by increasing HR
- In absence, effect of drug is stronger
- Lack of CCR to heroin means the effect is stronger
What is the CCR a form of?
Tolerance
How are the effects of tolerance complex?
- Can be a form of homeostatic protection to reduce harmful effects
- Can also lead to overdose if contextual cues are absent
What causes a craving?
Withdrawal symptoms
What has research with rats shown?
Animals prepared to work hard to receive stimulation of nucleus accumbens
What did Wise discover?
Anhedonia hypothesis
What is the anhedonia hypothesis?
Dopaminergic synapses convey ‘goodness’ (e.g. food)
How was Wise’s Dopamine and reinforcement experiment carried out?
- Rats trained to press lever to obtain food, then split into 3 groups
- G1 - lever pressing reinforced by food
- G2 - no longer reinforced - rats stop pressing lever
- G3 - given dopamine antagonist and reinforcement continued
What was the result of Wise’s experiement?
3rd group showed similar disengagement as group 2 despite continued reinforcement
What was commonly found among long term drug users?
Drug taking overtime results in less euphoria - reduction in ‘high’ but craving increases
What is the incentive salience theory?
Dopaminergic circuit involving NA and VTA is not so much responsible for pleasure obtained but motivation to obtain
What else does the IST theory propose?
Addicts become sensitised to drugs because their use affects the motivation related dopaminergic synapses in their brain
What is Comorbidity?
The probability of a diagnosis of drug or alcohol dependence increasing with the severity of a mental illness
How can drug use cause mental illness and vice versa?
Drug use –> neurotoxicity –> MHP
MHP –> self-medication –> Drug use
Why do people use drugs to cope?
Self medication due to comorbidity
