Week 5

Question 1

Why is reward responsively necessary in animals

Answer 1

It contributes to survival and reproduction by reinforcing behaviours the yeild successful or pleasurable outcomes

Question 2

Describe what areas of the brain are related through reward. Mention intracranial self stimulation

Answer 2

When a rat was implanted with electrodes in the areas of the brain such as the nucleus accumbens, hypothalamus and amygdala it repeatedly tapped a lever to send electricity to these parts because it would activate them and make the rat feel good

Question 3

What is the role of the nucleus accumbens, hypothalamus and amygdala in terms of reward

Answer 3

The nucleus accumbens allows pleasure and euphoria the hypothalamus plays a role in opioid addiction and the amygdala plays a role in learned reward

Question 4

What is the mesolimbic dopamine pathway

Answer 4

It is a reward pathway composed of the ventral tegmental and lateral hypothalamus, nuclues accumbens, amygdala, spetum and prefrontal cortex. these areas are all connected bu the medial forebrain bundle which is a bundle of dopaminergic neurones which projects axons from the VTA to all the mentioned areas

Question 5

What are endorphins

Answer 5

Chemicals which work to suppress pain and increase pleasurable experience

Question 6

Explain how endorphins affect reward by reducing gaba’s inhibitory effect of dopamine release

Answer 6

Dopamine is released in the brain when we experience pleasure, gaba is an inhibitor which reduces the amount of dopamine being released when heroin or morphine are introduced to the brain they inhibit the ability for GABA to regulate the amount of dopamine so higher levels or dopamine continue to be released. The leads to increases feelings of pleasure

Question 7

Describe how drug use leads to changes in the brain

Answer 7

Drug taking leads to people choosing drugs over non drug incentives. They dont have pleasure from doing anything else in their life. And drug taking leads to much higher dopamine release and therefore reinforcement this makes the habits resistant to extinction due to the extend of the dopamine reaction from the drug. Some drugs release 2 to 10 times more dopamine than daily pleasurable activities

Question 8

How does brain activation to reward differ at different ages

Answer 8

Young people show activation of the nucleus accumbens when anticipating reward while older people do not and upon receiving reward younger people show more areas of brain activation than older people

Question 9

What is the genetic theory of addictin

Answer 9

Just taking drugs is not sufficient for addiction there must genetic susceptibility. Family, twin and adoption studies show heritability. And animal studies show that animals can be bread to prefer alcohol

Question 10

What is the family heritability rate for first degree family member and multi-generation addiction

Answer 10

3-4 times higher prevalence of alcoholism in first degree family members and 9 time greater prevalence in those with multigenerational alcoholism

Question 11

What are some arguments against heritability of alcoholism

Answer 11

Many non genetic characteristics run in families e.g if your family supports and football team u will too it not because of genetics
Parents also pass down attitudes about drug use so if your parents love drinking u might too
Parents also predict drinking expectansies in children so if u see your mum having a good time while drinking u may expect the same outcome for yourself

Question 12

Describe evidence for the genetic theory of addiction in animal studies

Answer 12

Animals bread from ‘alcoholic’ parents display animal seeking behaviours
Sensitivity to alcohol
Tolerance
Higher rates of metabolism
Vulnerability to withdrawal seizures

Question 13

What is the ALDH2-2 polymorphism

Answer 13

ALDH2 codes for an enzyme that breaks down alcohol acetic acid. Most people have to copies of this gene, one from each parent. ALDH2-2 is a mutation which renders ALDH2 inactive which reduced the ability to metabolise alcohol leaving people feeling sick and is also responsible for the ‘asian flush’

Question 14

Describe the link between ALDH2-2, ALDH2 and alcoholism

Answer 14

Alcoholics are more likely to have ALDH2 compared to control which could signify that having ALDH2-2 is a protective factor since and inability to metabolise alcohol leave u feeling sick

Question 15

What is evidence against the link between ADLH2-2 and alcoholism

Answer 15

Previous findings are based on asains and we have not ALDH2-2 in caucasians so it cannot explain alcoholism in white people

Question 16

Discuss genetic theories of addiction concerning the D2 receptor subtype and A1 allele

Answer 16

Alcoholism is associated with the A1 receptor subtype or the D2 receptor. The A1 allele has fewer postsynaptic dopamine receptors so people use drugs to compensate as they increase dopamine

Question 17

Explain the incentive sensitisation theory

Answer 17

Repeated drug use cause neurological changes producing sensitisation to the drug this leads to motivation to keep recreating the drug state. This keeps people wanting to the drug even in the absence of liking it. Especially since dopamine is most involved in the wanting pathway rather than the liking one

Question 18

What are common cognitive changes which occur in people dependent on alcohol

Answer 18

Impulsivity/sensitivity to reward
Decision making
Ability to foresee longterm outcomes
Memory

Question 19

Give and example of an inability to foresee longterm outcome

Answer 19

If a smoker hasnt smoked in 24 hours and they are giving the option to have 1 smoke or wait a day and receive a whole pack they will choose the one smoke

Question 20

What is the somatic marker hypothesis of addiction

Answer 20

When the desirable outcome you thought you were going to instead become negative there is a drive to change behaviour but with with addiction dont do this, they keep repeating that same behaviour because the brain is not receiving the correct signals to re adapt are not being sent or received properly