Role of Dopamine in Addiction

Question 1

What do the abbreviations ‘VTA’ and ‘NAc’ stand for?

Answer 1

• Ventral Tegmental Area.

- Nucleus Accumbens.

Question 2

Addictive Behaviours trigger the release of (blank) in the (blank), which creates a sense of pleasure in the (blank)

Answer 2

• Dopamine.
• Ventral Tegmental Area.
• Nucleus Accumbens.

Question 3

What is the Reward Pathway?

Answer 3

• Part of the Mesolimbic Pathway.
• Evolved: usual adaptive response to good-for-us behaviours (eating).
• Addictive Behaviours: system responding to harmful actions = maladaptive.
• Addictive Substances: trigger dopamine release in reward pathway (humans + animals).

Question 4

Give an example of the reward pathway responding in a maladaptive way.

Answer 4

• Gambling Task: dopamine levels increased regardless of win/loss (Joutsa et al, 2012).
• Alcohol: dopamine levels increased (Boileau et al, 2003).

Question 5

How does Tolerance work?

Answer 5

• Develop tolerance over time.
• Dopamine receptors = less sensitive to effects.
• Decrease in D2 Receptors and Dopamine Release (Volkow et al, 1997).
• Have to engage more for same sensation.

Question 6

How does Tolerance link to Withdrawal Symptoms?

Answer 6

• Developed tolerance and lowered sensitivity = must engage more for same sensation and so stopping causes unpleasant withdrawal symptoms.
• Becomes more about avoiding withdrawal rather than the initial pleasure.

Question 7

What area of the brain is vital in maintaining addiction?

Answer 7

• The Frontal Cortex.

Question 8

Complex processes are involved in (blank) and causing (blank) even after (blank) disappear.

Answer 8

• Maintaining addiction.
• Relapse.
• Withdrawal symptoms.

Question 9

Volkow suggested that the dopamine reward pathway is a starting point, but what is really responsible for turning a behaviour addictive?

Answer 9

• Changes in the frontal cortex.

Question 10

What is the Frontal Cortex usually linked with?

Answer 10

• Higher cognitive functions (decision-making + memory).

Question 11

How can addictive behaviours alter our brains? Give an example.

Answer 11

• Change brain circuits that usually decide what to pay attention to; attach too much importance (salience) to behaviour and associated cues.
• Dopamine System = want to engage rather than just enjoy it.

Question 12

Why do addicts continue with behaviours that they don’t enjoy?

Answer 12

• They can’t stop as they cannot overcome the cravings (Robinson and Berridge, 2003).

Question 13

What has research into cocaine addicts / addicts in general shown?

Answer 13

• Coke: Abnormalities in the frontal cortex (Volkow et al, 1992).
• Coke: Impaired performance in tasks using frontal cortex; decision-making (Bolla et al, 2003).
• Addicts: exposure to drugs/associated cues = increased activity in frontal cortex (Wang et al, 1999).

Question 14

Describe James Olds and Peter Milner’s 1954 research involving rats and electrodes.

Answer 14

• Electrode in particular region of rat’s brain was stimulated when rat went into certain corner of box.
• Findings: rat returned to corner as if experience was pleasurable hence name of ‘reward centre’ / ‘pleasure centre.’

Question 15

Describe the research involving rats and levers.

Answer 15

• Rats: repeatedly press lever to experience stimulation in this area, even forgoing eating.

Question 16

What type of addiction is the ‘pleasure centre’ usually used to explain, and what is one of the main processes?

Answer 16

• Usually explains chemical addictions.

- Main process: dopamine release in mesolimbic pathway.