Reward System Flashcards
What type of drivers do we have?
Extrinsiv and intrinsic
How d we react to a threat?
Avoidance
What does the reward system do?
Produces spikes in the release of dopamine in brain regions connected with pleasure to enhance motivation
Key Neurotransmitter + facts
Dopamine
–> not about the pleasure itself but the motivation towards it, spikes in anticipation
Effect of too much/little dopamine
To little = Depression or lack of motivation
Too much = addictive behaviours
Where are the dopaminergic pathways mostly located?
Limbic system and PFC
Functions of dopamine (4)
Reward and motivation
Fine tuning motor functions
Compulsion
Perseveration
Too much dopamine leads to …
Too little leads to …
Abnormalities lead to …
Addiction (mesolimbic)
Depression (mesocortical)
Schizophrenia
–> Hyperactive mesolimbic, hypolimbic mesocortical
Dopamine in neurodegenerative conditions
–> Parkinson’s
(dopamine deficiency in the nigostriatal pathway)
Dopamine in neurodevelopmental conditions
–> ADHD
(dopamine dysregulation, deficit in mesolimbic)
Parts of the dopaminergic pathways (9)
- Dopaminergic regions
- Dopaminergic receptive regions
- GABAergic projections
- VTA –> Dopamine production
- Striatum
- Nucleus accumbens
- Hipocampus
- Amygdala
- PFC
What is GABA?
neurotransmitter, inhibits excitatory response
Which is the dopamine-richest part of the brain?
Striatum
3 pathways for dopamine
- Nigrostriatal
- Mesolimbic
- Mesocortical
Nigostriatal Pathways
From substantia nigra to striatum.
Fine-tuning of motor functions
Mesolimbic
From ventral tegmental area to striatum. Reward and motivation
Mesorcortical
VTA to PFC.
Executive and cognitive functioning (planning and goal-directed motivation)
“wanting”
desire or motivation to obtain rewards.
–> dopaminergic pathways
“liking”
pleasure of hedonic aspect of rewards
–> mediated by opioidergic and endocannabinoids systems in areas like the nucleus accumbens
Are wanting and liking different?
Yes, very much so, but they’re related
–> dopamine plays a supporting role in controlling and enhancing hedonic pleasure
–> but there must be a balance between these
What is addiction?
A persistent release of dopamine produces an intense experience of wanting but not liking
–> this means that one gets desensitized as the pleasure derived gets lowers creating a self-destructive cycle
What happens when addiction progresses?
- Affects the PFC and limbic system
- Drug related cues get stored in amygdala and hippocampus turning everyday shit into triggers for wanting a drug
Dopamine and Addiction
- higher dopamine levels in the mesolimbic pathway is liked to addiction
When addicted one’s —- undergoes sensitization to wanting and one’s —- becomes desensitized
wanting // liking
Reinforcement system
Wanting –> anticipates the reward
(dopamine release)
Liking –> experiencing the reward
(dopamine release)
–> Leads to learning through strengthening neural connections associated with rewarding behaviour. Strengthens both wanting and liking
Parts of addiction
- Chronic flooding of dopamine changes brain structure
- Increased sensitivity in ‘wanting’ system
- brain reacts to extra dopamine by reducing dopamine receptors
- this decreases responsiveness in the liking system
- we also lose the ability to enjoy natural things
Developmental aspect of reward
- Developmental mismatch
- In teenage yrs, striatum dominates PFC
(reward becomes more engaging, encourages more impulsivity in exchange for rewards) - then in adulthood PFC is stronger and controls the striatum
(promotes stable decision making and impulse contro)
What happens from teen to adult yrs>
Shift from unregulated to regulated reward system
Intrinsic motivation
- Natural tendency, driven by internal rewards
- Doing things for their own sake
- Self-rewarding, self-sustained, healthy
- natural capacity
Pros of intrinsic motivation
- People tend to have greater excitement and confidence
- more creativity
- persistence
Self-determination theory
- dictates that theres 3 innate psychological needs for intrinsic motivation
1. Autonomy
2. Belonging
3. Competence
Autonomy
Act by choice, not by external demands, have at least some control in the process
Belonging
need to feel connected to others, feeling valued by others, social need
Competence
Our need to feel a sense of growing mastery, engaging in activities that further promote the growth of our abilities
Extrinsic motivation
A motivation to participate in an activity based on meeting an external goal, garnering praise and approval, winning a competition, or receiving an award or payment.
Downsides of extrinsic motivation
When external rewards become too controlling, our intrinsic enjoyment reduces
Undermining effect
When a task is linked to a performance-based rewards, individuals may lose the intrinsic value of succeeding in the task
Proof for undermining effect
- in brain scans,
–> The anterior striatum shows less activity
–> decreased engagement on the right lateral PFC during the task
–> Both limbic (impulsive desire) and PFC (cognitive control) activities decrease-
How does modern affect dopamine?
- The reward system originated to reinforce survival behavivour
- but now minimal effort yields instant rewards
- so wer’re overwhelmed with dopamine surges which isn’t great
Consequences of quick rewards
- Reduces dopamine receptor availability and function
- Overreliance on instant rewards
- Fostered dependency ie addiction
How to protect our reward system (7)
- Awareness
- Eat nutrient-dense antiinflamatory foods to support pathways
- Engage in physical activity
- Manage stress
- Form strong social support systems
- cultivate habits supporting intrinsic motivation
- Balance long and short term pleasures
