6.4 Addiction

Question 1

Conscious vs unconscious behaviour

Answer 1

Unconscious: does not require intentional thought (e.g. reflex)

Conscious: voluntary movement designed to satisfy a need or want

Question 2

In terms of behaviour, what is a drive?

Answer 2

Excitatory state produced in response to disturbance of homeostasis

Question 3

What are the two main types of drives?

Answer 3

• Psychosocial: external (e.g. make money)
• Biological: internal (e.g. drink water)

Question 4

Describe how drives and reinforcements interact to create motivations

Answer 4

• You have a drive (e.g. hunger)
• You happen to eat
• Now you are less hungry (positive reinforcement)
• Now, when you are hungry, you are MOTIVATED to eat food

Question 5

What is a useful definition of motivation?

Answer 5

A desire to act in service of a goal (pulling the glass)

Question 6

Where do the dopaminergic neurons of the mesolimbic pathways arise from? Which other pathway do they supply?

Answer 6

• Ventral tegmental area
• The neurons that supply dopamine to the mesoCORTICAL pathway also arise from the VTA

Question 7

In two words, summarise the role of the mesolimbic pathway

Answer 7

Reward processing

Question 8

What is the role of the mesolimbic pathwya in motivation?

Answer 8

• Connects to various brain regions such as amygdala, nucleus accumbens, and hippocampus
• It is responsible for mediating reward responses, prompting us to seek out rewarding stimuli again

Question 9

What is the main role of the nucleus accumbens?

Answer 9

Reward/reinforcement mechanisms.

Question 10

What is the role of the mesocortical pathway?

Answer 10

Integrates information about reward processing with conscious effort (e.g. I will read this book so I learn this thing so I make money so that I can have more freedom)

Question 11

Behaviourally, what is a reward?

Answer 11

A stimulus that produces positive experience

Question 12

What are the two kinds of reward?

Answer 12

Primary: necessary for survival
Secondary: One degree removed from primary (e.g. money = food)

Question 13

What happens to dopamine release from the VTA in a negative prediction error?

Answer 13

It decreases below tonic baseline.

Question 14

A buyer purchases your product. Will their dopamine release be higher or lower if it takes longer to be delivered?

Answer 14

• Lower
• Value equation: effort and sacrifice

Longer delay = lower dopamine

Question 15

You want to buy a bunch of useless house plants, but you need to go to work to get money to do so? On a long enough time horizon, what can happen to the dopaminergic response?

Answer 15

Over time, the dopaminergic response will be brought forward in the process (i.e, dopamine may be released in response to the money, not just the reward).

NOTE: This is not a primary vs secondary reward situation, because house plants are not necessary for survival.

Question 16

Liking vs wanting

Answer 16

Liking: positive emotions related to pleasure

Wanting: desire for reward/goal triggered by cues (incentive salience)

Question 17

Are liking and wanting linked processes in terms of reward mechanisms?

Answer 17

• No
• Dissociable

Question 18

Does the dopaminergic transmission throughout the mesolimbic/cortical pathways mediate liking or wanting?

Answer 18

• Wanting, of course!
• How could it be any other way?

Question 19

What are hedonic hotspots? Where are they? Do they mediate liking or wanting?

Answer 19

• Collections of brain structures scattered throughout limbic structures
• Mediate pleasure response (e.g. liking)

Question 20

How does methamphetamine hijack neural reward circuitry?

Answer 20

• Increases dopamine release presynaptically
• Slows reuptake

Question 21

How does cocaine hijack neural reward circuitry?

Answer 21

Blocks presynaptic reuptake of dopamine (this is its primary function)

Question 22

How does alcohol affect the CNS? How does this influence reward mechanisms of the brain?

Answer 22

Overall effect: depressant (increase GABA by increasing GABAa receptors, decrease glutamate by inhibiting NMDA)

Also increases activity of opiodergic neurons in the ventral tegmental area. This decreases GABAergic interneurons, removing the brake from VTA dopamine neurons

Question 23

What is addiction?

Answer 23

Compulsively engaging with a rewarding stimulus despite negative consequences

Question 24

What are the three hallmarks of addiction?

Answer 24

• Tolerance
• Withdrawal
• Craving

Question 25

What are some common hallmarks of substance use disorder within diagnostic guidelines?

Answer 25

• Taking more than intended
• Unsuccessful attempts to reduce use
• Preoccupation
• Social impairment
• Addiction: withdrawal, craving, and tolerance

Question 26

Outline the biopsychosocial model of addiction

Answer 26

• Biological: heritability (e.g. polymorphisms in reward pathways)
• Psychology: personality traits (neuroticism/impulsivity increase risk)
• Social: Socioeconomic status, availability (e.g. fentanyl in ‘Merica)

Question 27

What are the three components of the cycle of substance use disorder, and which parts of the brain do they relate to?

Answer 27

1. Binge/intoxication (incentive salience; mesolimbic pathway)
2. Negative affect/withdrawal: mediated by amygdala
3. Preoccupation/anticipation: dysfunction in executive function (various aspects of prefrontal cortex)

Question 28

How does the “cycle” of substance abuse shift as addiction moves from acute to chronic?

Answer 28

Acute: seeking pleasure by taking substances

Chronic: seeking relief from withdrawal

Question 29

What happens to wanting and liking as an addiction progresses? Relate this to underlying neural circuitry

Answer 29

• Wanting increases, due to increased activity in mesolimbic pathway
• Liking decreases, as activity in hedonic hotspots decreases.

Question 30

In response to substance abuse disorder, the dopamine system is downregulated. What are the consequences of this?

Answer 30

• Less response to natural rewards
• Tolerance
• Craving/preoccupation