Task 4 - Reward system

Question 1

What is phasic dopamine and what does it signal?

Motivation circuit

Answer 1

Phasic dopamine (rapid, short, in response to a stimulus) signals an unexpected reward or a prediction error

Dopamine response = Reward received - Reward expected

Question 2

Reward prediction error hypothesis

Schultz

Answer 2

Dopaminergic midbrain neurons and their targets respond at two points in time:
1) In response to the appearance of a reward predicting stimulus
2) In response to omission or receipt of the reward

Question 3

Blocking paradigm

Answer 3

Stimulus is blocked if its paired with already fully predicted reward value (if you present a cue and it works well and then suddenly present a second one there is no need, so no learning)

Question 4

Conditioned inhibition paradigm

Answer 4

Stimulus presented simultaneously with established reward-predicting stimulus, but not reward given afterwards (= conditioned inhibitor predicts
explicit absence of reward)

Question 5

Primary reinforcers

Answer 5

Also called unconditioned reinforcers
Examples: Food, water, sex
Trigger direct activity in the ventral striatum (VS)

Question 6

Secondary reinforcers

Answer 6

Also called conditioned reinforcers
Examples: Money, points
Also activate the nucleus accumbens (NA) and VS

Question 7

Orbital frontal cortex (OFC)

Function

Answer 7

Assigns the object representations of the external world with their corresponding values of the associated expected outcome (object-value association)