Addiction

Question 1

What is an addiction?

Answer 1

• An inability to stop doing something harmful or using something, especially something harmful. (dictonary)

Question 2

What are the symptoms of addiction?

Answer 2

• Compulsive behaviour
• Craving
• Intrusive thoughts
• Mood swings
• Neglect of responsibilities
• Secrecy

Question 3

What are the componenets of a reward?

Answer 3

• Evolved system to identify and secure beneficial features of the environment (and avoid harm)

1. Reward recognition
2. Reward Prediction
3. Learning and memory
4. Reward seeking
5. Motivated behaviour

Question 4

Where is the reward centre of the brain?

Answer 4

• Nucleus accumbens but involves multiple regions

Question 5

How is dopamine involved in reward?

Answer 5

• Pharmacological enhancement of dopamine transmission (cocaine, DR agonists) promotes arousal, locomotion and motivation for exploration
• Parkinson’s patients on L-DOPA at risk of compulsive/impulsive behaviour aas a side effect of treatment
• Antagonists of dopamine receptors cause anhedonia and avolition
• Lesions in ventral tegmental area and nucleus accumbens abolish reward learning and seeking

Question 6

What is the nueroanatomy of dopamine cicuitry?

Answer 6

Mesolimbic and mesocortical pathways plus feedback loops

Question 7

What are intincsic rewards?

Answer 7

• Something that directly causes pleasure
• Sweet foods, social praise, beauty, sex

Question 8

What are extrinsic rewards?

Answer 8

• Something that is linked indirectly to pleasure
• Money, good grades, exploration

Question 9

What is associative learning?

Answer 9

• Pavlovian conditioning (bell ring=food)
• Reward error prediction
• Association of cue with reward

Question 10

What is pleasure?

Answer 10

• Sensation of gratification/joy
• Euphoria
• Bliss
• Opiods and cannabinoids can induce pleasure pharmacologically

Question 11

What are Hedonic hotspots?

Answer 11

• Infusion of opiods or cannabinoids into nucleus accumbens can map local ‘hotspots’ for pleasure
• Hotspots can enhance or suppress pleasureable sensation of intrinsic rewards (e.g. sucrose)
• Hotspots can be plastic - range and valence of effect can be altered

Question 12

What is the difference between wanting and liking?

Answer 12

Dopamine drives:
* Reward prediction and associative learning
* Reward seeking and motivation
* ‘Wanting’

Endorphins and endocannabinoids drive:
* Euphoria
* Gratification
* ‘Liking’

• Processes can become uncoupled

Question 13

Explain the timing of dopamine?

Answer 13

• Dopamine release swtiches from reward recognition to reward anticipation
• Learned association with cues
• Promotes reward seeking behaviour

Question 14

Describe the transition to addiction?

Answer 14

• Reward prediction drives anticipation
• Environmental cues initiate reward seeking
• Habitual behaviour
• REINFORCEMENT
• Compulsion
• Tolerance/habituation
• Intrusive thoughts
• Mood repair (craving rather than liking)
• ADDICTION

Question 15

Describe pleasure-reward loops.

Answer 15

1. Feedforward and feedback loops between nucleus accumbens (ventral striatum) and many other brain regions
2. Understanding reward conceptually
3. Emotional context of reward

Question 16

Explain the importance of the prefrontal cortex?

Answer 16

• Optogenetics allows targeted control of dopamine neurons with diff wavelengths of light, and modulation by cortical neurons

Question 17

Explain what ‘executive control’ over habits means?

Answer 17

• Feedback to VTA-striatum from mPFC suppresses reward seeking behaviour (seek dopamine release)

Question 18

How many stimuli use these circuits (reward etc)?

Answer 18

• Appetite
• Sexual
• Romantic
• Social
• Familial
• Status
• Prizes
• Music
• Pharmacological

Question 19

What are behavioural addictions?

Answer 19

• Contentious area of research
• Compulsive behaviours linked to reward seeking
• Usually defined by an excessive impact on everyday life e.g:
  1. Gambling
  2. Shopping
  3. Eating
  4. Sex
  5. Social media?

Question 20

What are supernormal stimuli?

Answer 20

Concept in relation to animal behaviour
* Seagull chicks will peck model beaks for food
* A patterned stick was a ‘supernormal stimulus’

• Human analogies:
  1. Social media
  2. Sweet/fatty foods
  3. Pornography

Question 21

What are addictive drugs?

Answer 21

• Develop physiological dependance
• Most linked to modulation of dopamine or opiod signalling
  1. Alcohol
  2. Cocaine
  3. Amphetamines
  4. Heroin
• Some are also more general stimulants
  1. Caffeine
  2. Nicotine

Question 22

What is negative reinforcement?

Answer 22

‘Anti-reward’ system:
1. Withdrawal from addictive drugs is aversive
2. Negative reinforcement

Hormonal influences
1. Rising cortisol as use persists
2. Stress response

Dynorphin hotspots
* Neuropeptide modulator
* Presumed k-opiod receptor agonist

Question 23

Summarise addiction

Answer 23

• Addiction is a complex mental state defined by compulsive reward-seeking behaviour despite harmful consequences
• Reward system centred on mesolimbic and mesocortical dopamine pathways
• Wanting (dopamine driven) and liking (Opiod and cannibinoid driven) can be distinguished
• Dopamine signals reward prediction errors, leading to anticipation and reward seeking
• Wide range of stimuli are rewarding
• Substance abuse leads to dependance and negative reinforcement