W9L1 - Dopamine Flashcards
What are the 2 areas releasing and synthesizing dopamine
- ) Substantial Nigra (SN)
2. ) Ventral Tegmental Area (VTA)
What does VN do
Motor Control
What does VTA do
Motivation and emotional responses (reward and addiction)
Where does VN and VTA send to
Amygdala, Nucleus Accumbens (NAc), PFC, Straitum
How does dopamine synthesize
Tyrosine > Dopamine > Dopamine > Noradrenaline
What is tyrosine
Amino acid found in food
What is between tyrosine > dopamine
Tyrosine hydroxylase
What is between Dopa > Dopamine
Amino Acid Decarboxylase
What is between Dopamine > Noradrenaline
Dopamine β-hydroxylase - Synthesize and breaks dopamine
What causes PD
Death of dopamine in substantial nigra
What are symptoms of PD
Initial: motor tremor; later: cognitive and EF impairments like dementia
What is the cure for PD. What is the problem
No cure, but symptoms can be reduce. However, it may cause addictive behaviours.
What does “reward” represent
Real, symbolic, or virtual
What happens when an unexpected reward is presented
DA burst
What happens when an expected reward is presented
No da burst on reward on set, DA burst on beep onset
What happens when expected reward but not given
Suppressed da burst on reward on set, DA burst on beep on set (as usual)
What does DA code
Reward and Effort Cost
What are effort costs
Every other rewarding thing one could be doing
When will effort task persistence endure
when the incentive of goals outweighs the cost
What happens when there is a low success cognitive task
effort cost > incentive = waste of time
Why is gambling addictive
Unexpected large wins = DA coded as positive despite overall loss
What is drug addiction
Compulsive drug-taking and drug-taking at expanse of other activities AND despite adverse consequences
What does cocaine do biochemcially
Blocks reuptake of dopamine > flood dopamine with system
What is ice and speed. What happens biochemically.
Ice: more pure; speed: less pure
Not only blocks, but reverse uptake transporter actively expelling DA and NA out of the neuron
What is methylphenidate (ritalin)
Blocks reuptake of DA and noreadrenaline
How do addictive drugs work with reward response
Brain always codes reward better than expected due to DA release. Quicker release = More Addictive
Does quicker DA release = addictive?
Not always. Might be more important in behaviour and cognitive control rather than euphoric feeling. (Some addictive drugs less DA than other less-addictive)
Euphoric = Opioid system
Drugs and Free Will Problem
- Drugs initiative craving
- Impaired cognitive control/PFC caused by excessive dopamine
> Cognitive control + Craving = Addiction
