Lecture 5

Question 1

Causal Question’s explainations in the role of DA in reward:

Answer 1

1. “liking”
2. Learning
3. “wanting”

Question 2

Experimental approaches to determine what DA does in reward: what reward function is _______

Answer 2

1. Necessary cause (lost)
2. Sufficient cause (enhanced)
3. coding of function (coded)

Question 3

Answers of Causal DA Question (1/4)

Answer 3

1. Activation sensorimotor hypothesis of effort, arousal and response vigor

Question 4

Answers of Causal DA Question (2/4)

Answer 4

2. Hedonia hypothesis of reward pleasure

Question 5

Answers of Causal DA Question (3/4)

Answer 5

3. Reward learning hypothesis of associative stamping-in, teaching signals and prediction errors

Question 6

Answers of Causal DA Question (4/4)

Answer 6

4. Incentive Salience hypothesis of reward “wanting”

Question 7

(A: 1/4) Activation-sensorimotor hypothesis

Answer 7

DA mediates general functions of: action generation, effort, movement, general arousal/behavioural activation.

Question 8

(A: 2/4) Hedonia hypothesis

Answer 8

DA in NAc is a “Pleasure neurotransmitter”: Mediates +ve reinforcing effects of reward stimuli. Supress DA~Anhedonia

Question 9

DA and Hedonic Rxn’s in rats

Answer 9

DA reduction does NOT decrease “liking”

DA activation does not increase “liking”

Question 10

5 different brain manipulations insufficiently enhancing hedonic impact of reward

Answer 10

1. Hyper-DA mutation (KO mice)
2. AMPH injected in NAc
3. AMPH systemic administration
4. Sensitization
5. Electrical brain stim reward

Question 11

DA and Hedonic Rxn’s in humans

Answer 11

DA does NOT mediate subjective ratings

Question 12

DA does NOT mediate subjective ratings w/ two methods:

Answer 12

1. Patients with Parkinsons show normal liking ratings

2. DDS patients have compulsive actions due to more L-Dopa administered.

Question 13

Nonhedonic hypotheses of reward (two main)

Answer 13

1. Reward learning

2. Incentive Salience

Question 14

(A: 3/4) Reward Learning hypothesis

Answer 14

DA signal modulates synaptic plasticity in target neurons, psychologically suggesting DA acts to etch links (in neostriatum and NAc) b/w S-S and S-R events.

Question 15

Reward-Learning (DA) Hypotheses (3 types)

Answer 15

all say DA mediates learning but in different ways

1. DA signals stamp in S-R and S-S associations whenever reward follows
2. DA activation causes new habit learning (ergo habit performance)
3. DA mediate teaching signals via US prediction errors

Question 16

Reward-Learning (DA) Hypothesis (1/3): Associative stamping in

Answer 16

DA acts as US reinforcement signal to learn associations about preceding reward stimuli. Based on Law of effect (thorndike)

Question 17

Reward-Learning (DA) Hypothesis (1/3): Associative stamping in: Thorndike’s Law of effect (3 components)

Answer 17

1. Context (S)
2. Instrumental response (R)
3. Response outcome (O)

Question 18

Reward-Learning (DA) Hypothesis (1/3): Associative stamping in: Thorndike’s Law of effect (summary)

Answer 18

if R in presence of S followed by satisfying event~ S-R association strengthened
If R in presence of S followed by unsatisfying event~S-R association weakened.

Reinforcer (O) “stamps” S-R association

Question 19

Reward-Learning (DA) Hypothesis (1/3): Associative stamping in: Supporting Evidence

Answer 19

• Extinction-mimicry
• DA modulating mechanisms of LTP and LTD
• DA manips right after learning trial alters consolidation.reconsol of memories

Question 20

Reward-Learning (DA) Hypothesis (2/3): Habit Learning

Answer 20

DA causes new S-R habits to be learned &/or modulates strength of learned S-R habits

Question 21

Reward-Learning (DA) Hypothesis (3/3): Prediction Error Learning Model(s)

Answer 21

suggest DA embodies specific parameters of learning equations by acting as a teaching signal.

1. Rescorla-Wagner Model
2. Temporal Difference Model

Question 22

Reward-Learning (DA) Hypothesis (3/3): Prediction Error Learning Model (a) Rescorla-Wagner Model

Answer 22

suggests DA boosts might increase predictions of future reward (V) to a (CS). Increase in DA elevates prediction error (lambda-V) generated by hedonic impact of US (lambda) at moment of reinforcement, boosting amount of learning on the trial (deltaV).

Question 23

Reward-Learning (DA) Hypothesis (3/3): Prediction Error Learning Model (b) Temporal Difference Model

Answer 23

time more explicit in expectations of reward as series of future events. V becomes more accurate thru learning about actual rewards via prediction errors that modulate synaptic weights in circuits involved in future predictions.

Question 24

DA makes _____ contributions to both ____ & ____, but not directly causing _______

Answer 24

Indirectly, learning, learned performance, formation of new reward associations

Question 25

Evaluation of DA’s direct roles (divided into 3 questions)

Answer 25

1. is DA a necessary cause?
2. Is DA a Sufficient cause?
3. DA neuronal firing patterns?

Question 26

Is DA necessary cause?

Answer 26

unneccessary for normal reward learning, ergo not a cause. DA contributes to learning as teaching signal, prediction error or Stamping-in mechanism

Question 27

Is DA a sufficient cause?

Answer 27

showed increased “wanting” but not “liking”.

Question 28

DA neuronal firing?

Answer 28

DA neurons may code informational consequence of learning signals. Hypothesized to be incentive motivation.

Question 29

(A: 4/4) Incentive Salience hypothesis: central premise

Answer 29

Reward is composite of wanting, liking and learning.

DA only mediates “wanting” portion.

Question 30

Incentive salience is NOT:

Answer 30

a) hedonic “liking, nor sensory pleasure

b) reducible to learning

Question 31

Incentive salience is:

Answer 31

a motivational transformation of a reward-related neural representation (ie: percieved or recalled CS or US).

Question 32

Incentive salience value of stimulus is generated by

Answer 32

mesolimbic systems each time reward stim occurs and pre-existing reward related associations

Question 33

DA= _____

Answer 33

Incentive salience

Question 34

Important that Incentive salience combines:

Answer 34

Mesolimbic dopamine system mechanisms AND Physiological states

Question 35

Motivational magnets

Answer 35

CS produced by Incentive salience.

Question 36

Incentive Salience theory step 1:

Answer 36

1. CS “wanting” assignment based on “liked” US. predictors go from neural to desired. The hedonic activation by new US.

Question 37

Incentive Salience Theory step 2:

Answer 37

2. CS “wanting” reboosting. Steps are appetitive. Associative-learning between, strengthens the incentive salience assignment to rewarded stimuli.

Question 38

Reboosting

Answer 38

keeps up motivation for long-term. Keeps it wanted for later trials. Reboosting keeps the reward relevant. counters extinction mimicry.

Question 39

Extinction Mimicry

Answer 39

gradual falling off of consummation of a well-established reward

Question 40

Incentive Salience Theory step 3:

Answer 40

Attribution of “wanting” to a CS. making the CS more “wanted” by route of the reboosting of stage 2 and adds physiological states of each reward introduction.

Incentive Salience of CS becomes a conditioned motivational response