3.2.2 Bio exp. 1: Dopamine

Question 1

What is dopamine?

Answer 1

It is a neurotransmitter which moves in the gaps between nerve cells to transmit messages

Question 2

What happens in initiation?

Answer 2

• Addictive substances activate the mesolymbic pathway in the brain known as the reward pathway
• Addictive substance or behaviour triggers the release of dopamine in the ventral
  tegmental area of the brain
• Leads to a sense of pleasure in the nucleus accumbens

Question 3

How have humans evolved a sense to pleasure?

Answer 3

-When engaging in activities such as eating or sex, the brain receives a hit of dopamine
-This response is seen as adaptive as it aids survival

Question 4

What do maladaptive behaviours lead to?

Answer 4

They release huge amounts of dopamine which makes the individual want to do the behaviour again which leads to a maladaptive reward pathway system

Question 5

What research did Boileau conduct?

Answer 5

• Conducted research with 6 participants who underwent a PET scan before and after an oral dose of alcohol
• Found that alcohol led to dopamine increases in the brain

Question 6

What is a neuroadaptation?

Answer 6

Brain adapts in response to experience and strives to reach an equilibrium

Question 7

What is tolerance?

Answer 7

• The repeated exposure to addictive substances causes a reduced sensitivity in dopamine release process
• Dopamine receptors become less sensitive to a higher dose is needed

Question 8

What two things does research show in those with addiction

Answer 8

Decreased D2 receptors and decreased dopamine release

Question 9

What did Volkow find?

Answer 9

Users of cocaine had a reduction in both the number of D2 receptors in the brain as well as reduction in release of dopamine

Question 10

What did Volkow suggest about the dopamine reward pathway?

Answer 10

Causes changes in the frontal cortex that turn what was once engaging behaviour into a addiction

Question 11

What happens to brain circuits responsible for paying attention?

Answer 11

• Brain attaches too much salience to addictive behaviours and cues associated with it
• The behaviours become main focus on their life

Question 12

How does the change in brain circuits change the addicts views towards addictive substance?

Answer 12

-Makes the individual want to engage in behaviour rather than just liking it
- Can no longer enjoy the experience but cannot overcome it

Question 13

How do brain changes help explain relapse?

Answer 13

• Brain changes lead to lasting memories of the substance or behaviour
• When an individual has given up substance they are exposed to environmental reminders such as being in a pub
• This leads to a release of a small amount of dopamine which causes individual to desire a greater dopamine reward so they turn back to addiction

Question 14

Which research supports the role of dopamine in addiction?

Answer 14

Boileau et al - Conducted research with 6 participants who underwent a PET scan before and after an oral dose of alcohol
- Found that alcohol led to dopamine increases in the brain
- However PET scans have questionable reliability randomly one substance was tested

Question 15

Which research challenges the role of dopamine in addiction?

Answer 15

Yoder et al - Compared dopamine activity in social drinkers (24) and alcoholics (21)
- Gave participants and alcohol infusion and conducted PET scans
- Found increase in dopamine activity in alcoholics only
- Suggests substance itself is directly linked to an increase in dopamine levels

Question 16

What are some of the methodological issues Nutt et al found in relation to the role of dopamine?

Answer 16

• Sample sizes are too small so low population validity so results not generalisable
• Samples often from Western society so have cultural bias
• Substance given in a lab through inhaler so issues with ecological validity due to lab setting
• Non human animals used so results hard to generalise to humans