6.4 Addiction Flashcards
Conscious vs unconscious behaviour
Unconscious: does not require intentional thought (e.g. reflex)
Conscious: voluntary movement designed to satisfy a need or want
In terms of behaviour, what is a drive?
Excitatory state produced in response to disturbance of homeostasis
What are the two main types of drives?
- Psychosocial: external (e.g. make money)
- Biological: internal (e.g. drink water)
Describe how drives and reinforcements interact to create motivations
- 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
What is a useful definition of motivation?
A desire to act in service of a goal (pulling the glass)
Where do the dopaminergic neurons of the mesolimbic pathways arise from? Which other pathway do they supply?
- Ventral tegmental area
- The neurons that supply dopamine to the mesoCORTICAL pathway also arise from the VTA
In two words, summarise the role of the mesolimbic pathway
Reward processing
What is the role of the mesolimbic pathwya in motivation?
- 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
What is the main role of the nucleus accumbens?
Reward/reinforcement mechanisms.
What is the role of the mesocortical pathway?
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)
Behaviourally, what is a reward?
A stimulus that produces positive experience
What are the two kinds of reward?
Primary: necessary for survival
Secondary: One degree removed from primary (e.g. money = food)
What happens to dopamine release from the VTA in a negative prediction error?
It decreases below tonic baseline.
A buyer purchases your product. Will their dopamine release be higher or lower if it takes longer to be delivered?
- Lower
- Value equation: effort and sacrifice
Longer delay = lower dopamine
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?
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.
Liking vs wanting
Liking: positive emotions related to pleasure
Wanting: desire for reward/goal triggered by cues (incentive salience)
Are liking and wanting linked processes in terms of reward mechanisms?
- No
- Dissociable
Does the dopaminergic transmission throughout the mesolimbic/cortical pathways mediate liking or wanting?
- Wanting, of course!
- How could it be any other way?
What are hedonic hotspots? Where are they? Do they mediate liking or wanting?
- Collections of brain structures scattered throughout limbic structures
- Mediate pleasure response (e.g. liking)
How does methamphetamine hijack neural reward circuitry?
- Increases dopamine release presynaptically
- Slows reuptake
How does cocaine hijack neural reward circuitry?
Blocks presynaptic reuptake of dopamine (this is its primary function)
How does alcohol affect the CNS? How does this influence reward mechanisms of the brain?
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
What is addiction?
Compulsively engaging with a rewarding stimulus despite negative consequences
What are the three hallmarks of addiction?
- Tolerance
- Withdrawal
- Craving
What are some common hallmarks of substance use disorder within diagnostic guidelines?
- Taking more than intended
- Unsuccessful attempts to reduce use
- Preoccupation
- Social impairment
- Addiction: withdrawal, craving, and tolerance
Outline the biopsychosocial model of addiction
- Biological: heritability (e.g. polymorphisms in reward pathways)
- Psychology: personality traits (neuroticism/impulsivity increase risk)
- Social: Socioeconomic status, availability (e.g. fentanyl in ‘Merica)
What are the three components of the cycle of substance use disorder, and which parts of the brain do they relate to?
- Binge/intoxication (incentive salience; mesolimbic pathway)
- Negative affect/withdrawal: mediated by amygdala
- Preoccupation/anticipation: dysfunction in executive function (various aspects of prefrontal cortex)
How does the “cycle” of substance abuse shift as addiction moves from acute to chronic?
Acute: seeking pleasure by taking substances
Chronic: seeking relief from withdrawal
What happens to wanting and liking as an addiction progresses? Relate this to underlying neural circuitry
- Wanting increases, due to increased activity in mesolimbic pathway
- Liking decreases, as activity in hedonic hotspots decreases.
In response to substance abuse disorder, the dopamine system is downregulated. What are the consequences of this?
- Less response to natural rewards
- Tolerance
- Craving/preoccupation
