#96 - Reward/Salience (1.5 hours)

Question 1

Explain the “drive reduction” theory of motivated behavior.

Answer 1

“Drive reduction” is based on the idea of internal “drives” driven by homeostasic disruption; an internal “drive” that one needs to reduce, like water/food.

However, this theory doesn’t explain all motivated behavior, like exploration, aggression, or mating. Binge eating, where you consume more than you need, is also not explained.

Drive motivation - focuses on internal stimuli.

Question 2

Explain the “incentive motivation” theory of motivated behavior.

Answer 2

“Incentive motivation” revolves around the idea of a “goal” and stipulates that behavior results out of the reward of the goal.

Incentive motivation - focuses on external stimuli

Question 3

What does dopamine neuron activity in the ventral tegmental area signal in regards to reward?

Answer 3

VTA Dopamine signals the relationship between the animal’s prediction regarding the reward and the reward itself.

This means, any time there is an unexpected “cue” or reward, dopamine firing will increase. If a cue happens but no reward is given, VTA dopa firing will decrease.

Dopamine = reward-prediction error signal.

Look at slide 18 for more info about experimental scenarios.

Question 4

Basic mechanism of action for cocaine/amphetamine

Answer 4

They block or reverse monoamine uptake mechanisms

Question 5

How is nicotine reinforced?

Answer 5

Its reinforcing effects are mediated through nicotinic receptors in the VTA, NOT!!! I repeat NOT!! the nucleus accumbens!

nicotinic ACh receptors are on dopamine neurons. When activated, they increase dopamine levels in the nucleus accumbens. Therefore, decreasing dopamine in the VTA will decrease reinforcement but inhibiting dopamine in the Nucleus accumbens will not.

Question 6

Basic mechanism of action for cannabis - how do they increase dopamine?

Answer 6

Cannabinoids inhibit GABA neurons in the VTA, disinhibiting dopamine neurons.

Question 7

Why do drugs of abuse thought to produce profound effects on the reinforcement system? 2 big reasons.

Answer 7

1) For normal stimuli, they get filtered through sensory channels, and other areas of the brain. Therefore, you get a small, regulated amt of dopamine. With drugs, they activate dopamine directly, getting an unregulated, large dose of dopamine.
2) Normally, if you do something with expected rewards, there will be no additional dopamine. With a drug, it directly activates dopamine, therefore it gets reinforced EVERY TIME you take it, at much higher levels.

Essentially, this means that every time you take the drug, there is a signal that the reward was WAY BETTER than expected!

Question 8

What does drive reduction theory fail to explain, as far as human behavior goes?

Answer 8

this theory doesn’t explain all motivated behavior, like exploration, aggression, or mating. Binge eating, where you consume more than you need, is also not explained. Also: simply eating more than you need because something tastes good.

Question 9

Which is more accurate describing human behavior, drive reduction or incentive motivation?

Answer 9

Neither. They both play important roles.

Question 10

What does “consummatory behavior” mean?

Answer 10

it means the behavior that is the consummation of the set of motivated behavior - eg, drinking.

Question 11

What is “appetitive behavior”?

Answer 11

behavior that brings the organism closer to the goal (eg, exploration, behavior to obtain food)

Question 12

t/f: both internal drive and incentive objects contribute to a “motivational state” in an organism.

Answer 12

True!!

Question 13

3 main points about motivated behavior

Answer 13

1. motivated behavior involves learned behavoir and innate systems/drives
2. Involves emotions and decision making.
3. Can be directed toward achieving something positive or avoiding something negative.

Question 14

How do different parts of the basal ganglia system handle different types of behavior, ie le basic/new learning vs. habits?

Answer 14

The accumbens core governs “goal seeking behavior,” while the dorsal striatum plays a larger role in “habit-based” behavior. Therefore, it is said that as a motivated behavior becomes learned better, the area governing the behavior moves DORSOLATERALLY.

Question 15

This region of the brain is responsible for integrating emotions and other abstract motivators (ie hunger) into concrete behaviors (ie, motor sequences.)

Answer 15

nucleus accumbens “turns emotion into action”

Question 16

T/F VTA Dopamine signals pleasure.

Answer 16

FALSE.

Question 17

T/F VTA Dopamine signals reward.

Answer 17

FALSE

Question 18

Simple way of describing VTA dopamine.

Answer 18

Dopamine = reward-prediction error signal, indicates difference between what is expected and what actually occurs.

Increases in firing = “better than expected rewards”
Decreases in firing = worse than expected rewards.

Question 19

What is “incentive salience”?

Answer 19

Reward associated stimuli can have a motivational “wanting” effect on the organism.

Question 20

Even though you are full, the waitress brings out a dessert plate and asks if you want dessert. Suddenly hungry, you order the brownie sundae. What concept led to your demise?

Answer 20

incentive salience!!
a cue associated with a reward (the sensory info in this case, seeing/smelling the food) can induce hunger and drive eating all on its own! even if you are full, it has a motivational wanting effect on you.

Question 21

T/F Dopamine acts to stamp in associations between cues and primary reinforcers.

Answer 21

True.

Question 22

T/F - evidence suggests that dopamine in the nucleus accumbens is critical for both learning about rewards and for driving motivated behavior.

Answer 22

True.

Question 23

3 characteristics of addiction

Answer 23

1. compulsion to seek and take drug
2. loss of control over use.
3. Negative emotional state when access to the drug is prevented.

Question 24

How do drugs of abuse, in general, become addictive?

Answer 24

They increase dopamine levels in the brain, which is critical for the reinforcing effects. They vary in how they increase dopamine, but they all do it.

Question 25

How do opioids exert addictive effects?

Answer 25

They disinhibit dopamine neurons in the VTA.

Question 26

Which monoamines does cocaine affect, from greatest to least?

Answer 26

SDN (cocaine is all about that serotonin)

serotonin>dopamine>norepi

Question 27

Which monoamines does amphetamine affect, from greatest to least?

Answer 27

NDS (reversal of cocaine)

Norepi >= dopamine > serotonin..

Question 28

You are doing an experiment where rats self-administer cocaine. Which region should you a dopamine antagonist to if you want to reduce the amount of “lever presses” (work) they will do before giving up?

Answer 28

Nucleus accumbens. It plays the largest role in reinforcing behavior, therefore, inhibiting it will reduce the breaking point the most.

Question 29

Pedunculopontine Tegmental Nucleus - important for the reinforcing effects of which drug?

Answer 29

nicotine

Question 30

T/F - Acetylchoine can increase dopamine through a variety of mechanisms, including lowering GABA and increasing glutamate.

Answer 30

true.

Question 31

T/F - THC self-administration will be blocked by a CB2 receptor antagonist.

Answer 31

False. CB1 antagonist is located in the CNS, and blocking it will stop self adminstration. CB2 - in the periphery.

Question 32

T/F An opioid antagonist like naltrexone will block THC self-administration

Answer 32

True! Opioid system is intricately involved with THC’s effects on dopamine neurons.

Question 33

T/F Cannabinoids increase synthesis and release of opioids.

Answer 33

true!!

Question 34

T/F - after withdrawal symptoms end, an “addict” will not experience cravings for their drug of choice.

Answer 34

FALSE. There has been long lasting changes in their ability to make decisions, they could relapse at anytime, long after withdrawals end.

Question 35

T/F in general, it is much easier to get people off a drug than to prevent them from relapsing.

Answer 35

True. Big problem with lots of research.

Question 36

Which drugs activate dopamine directly? Which activate dopamine indirectly?

Answer 36

Cocaine and amphetamine activate dopamine directly. Other drugs activate dopamine neurons in the VTA.