Task 4

Question 1

What are two key observations (illnesses etc.) that have historically dominated the understanding of dopamine function?

Answer 1

Severe movement deficits after dopamine-depleting lesions in Parkinson’s disease patients and reduced behavioral responses to motivating stimuli after interference with dopamine neurotransmission in experimental rats

Question 2

How is dopamine activity related to rewards?

Answer 2

Dopamine activity, as measured by electrophysiology or voltammetry, shows substantial increases related to rewards and reward-predicting stimuli​

Question 3

How does dopamine respond to reward uncertainty?

Answer 3

A slower, distinct electrophysiological response encodes the uncertainty associated with rewards​

Question 4

How do aversive events affect dopamine responses?

Answer 4

Aversive events produce slower electrophysiological dopamine responses, predominantly depressions

Question 5

What information does dopamine neurotransmission provide to the brain?

Answer 5

It provides differential and heterogeneous information to subcortical and cortical brain structures about essential outcome components for approach behavior, learning, and economic decision-making​

Question 6

How is the function of rewards defined?

Answer 6

By their action on behavior, not by affecting the brain through specific sensory receptors​

Question 7

What do identified midbrain dopamine-mediating signals signify?

Answer 7

They signify the pure reward value of objects, irrespective of their sensory components or the behavioral functions necessary to obtain them

Question 8

What constitutes the reward-prediction error in dopamine signaling?

Answer 8

The difference between predicted and obtained rewards,

crucial for reward-driven learning according to the Rescorla-Wagner learning rule​

Question 9

What is phasic activation in midbrain dopaminergic neurons?

Answer 9

Burst activity following primary food and liquid rewards, coding for the prediction error:
- such that an unpredicted reward elicits activation (positive prediction error)
- omission of a predicted reward induces a depression (negative prediction error)

Question 10

What indicates the importance of prediction errors for learning?

Answer 10

The block paradigm

shows that a stimulus is not learned as a valid reward-predicting stimulus if it is paired with an already fully predicted reward

Question 11

What happens in the conditioned inhibition paradigm regarding dopamine responses?

Answer 11

1. A test stimulus presented with an established reward-predicting stimulus
2. but no reward results in the test stimulus predicting the absence of reward,
3. not producing a dopamine-mediated response

Question 12

How do dopaminergic neurons code reward-prediction errors?

Answer 12

Dopamine response equals reward occurred minus reward predicted​

Question 13

What might the dopamine-mediated response to rewards constitute?

Answer 13

A neural basis of prediction error, conveying the crucial learning term of the Rescorla-Wagner learning rule

Question 14

What might dopamine-mediated signals influence in postsynaptic neurons?

Answer 14

Short- and long-term modifications of corticostriatal synaptic transmission​

Question 15

How might prediction errors contribute to behavior?

Answer 15

By establishing predictions, comparing current inputs with previous predictions, and emitting a prediction-error signal if a mismatch is detected

Question 16

How are responses to prediction errors graded?

Answer 16

Partial prediction errors induce smaller error responses, and responses co-vary with both magnitude and probability of reward

Question 17

How does the dopamine-mediated prediction-error response adapt over time?

Answer 17

It adapts to the mean and variance of the predicted probability distribution of reward magnitudes within the 2s stimulus-reward intervals​

Question 18

What roles do reward-predicting stimuli play?

Answer 18

• predict outcomes,
• provide advance information for decision-making,
• generate approach behavior
• serve as positive, conditioned reinforcers for earlier stimuli and actions​

Question 19

How do dopaminergic neurons respond to neutral and aversive stimuli?

Answer 19

They show generalized activation-depression responses if these stimuli are not distinctively different from reward predictors

Question 20

How is the reward prediction error signal conveyed in humans?

brain areas

Answer 20

It is conveyed to both the striatum and cortical areas, playing a central role in learning to optimize behavior

Question 21

What role does the dopaminergic system play in learning?

Answer 21

It helps make predictions based on past experiences, updating predictions when violated using a reward prediction error signal

Question 22

What do reinforcement learning models provide in terms of dopamine hypotheses?

Answer 22

A parsimonious account of many behavioral phenomena and neural activation patterns​

Question 23

What does human fMRI indicate about dopamine?

Answer 23

fMRI activations at or near dopaminergic midbrain nuclei and the ventral striatum correlate with both reward expectation and reward prediction errors

Question 24

How is the ventral striatum (VS) activated during learning trials?

Answer 24

The VS is activated during both expectation and receipt of rewards, with potentially stronger activations during the receipt phase

Question 25

What differentiates primary from secondary reinforcers?

Answer 25

Primary reinforcers like food, drink, and sex have a biological basis, while secondary reinforcers acquire their ability to strengthen behavior through association with primary reinforcers

Question 26

How do monetary rewards compare to primary rewards in fMRI studies?

Answer 26

Monetary rewards often elicit stronger and more robust activations in the nucleus accumbens compared to primary rewards like juice​

Question 27

How does the ventral striatum respond to social rewards?

Answer 27

It activates in response to diverse stimuli such as facial attractiveness, gaze direction, and images of romantic partners, similar to monetary rewards but at lower thresholds​

Question 28

How is cognitive feedback processed in the brain?

Answer 28

It often involves reward circuitry and is interpreted as a form of social approval, acting as a generalized conditioned reinforcer

Question 29

How can indirect learning reduce the cost of exploration?

Answer 29

By observing others and their consequences, helping to learn about the environment’s structure without directly engaging in costly or dangerous behavior​

Question 30

How does dopamine signaling change during the progression of cocaine use?

Answer 30

Phasic dopamine release in the dorsolateral striatum (DLS) emerges over weeks, while ventromedial striatum (VMS) dopamine signaling declines, indicating a shift in control from VMS to DLS during drug use