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Brain And Behaviour > Dopamine Function And Addiction > Flashcards

Dopamine Function And Addiction Flashcards

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1
Q

How do amphetamines work?

A

Increase release and decrease uptake via reversal of the uptake pump
Inhibits dopamine breakdown via MAO inhibition

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2
Q

What does high dose of systemic amphetamines dots a mouse?

A

Causes sterotypy - complex movements which are not goal directed)

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3
Q

What does low dose amphetamines cause in mice?

A

Hyperactivity

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4
Q

What are the possible explanations for dose dependanct reactions for amphetamines?

A

Larger release in dopamine within the NAc than striatum

Competition between behaviours

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5
Q

What behaviour is produced by amphetamines injection into the NAc?

A

Hyperactivity

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6
Q

What is the effect of amphetamine injection in the striatum?

A

Stereotypy

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7
Q

What is the explanation for hyperactivity as a result of amphetamines?

A

Environment has become more salient due to increas ein dopamine - manifestation of urge to explore new environment

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8
Q

What is operant conditioning?

A

Animal wil repeats behaviour is the consequence is rewarding e.g. Food, sex, water (driven by motivation)

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9
Q

IN the Skinner box what causes an increase in dopamine?

A

Receiving a reward or a stimulus which has previously been associated with the reward

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10
Q

What is the effect of a dopamine antagonist (Pimozide) on number of lever pressings on test days following conditioning?

A

They will decrease

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11
Q

What will happen to number o levers presses of no reward is given after conditioning?

A

They will decrease

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12
Q

What is the process by which an animal will decrease the number of times it presses the lever?

A

Extinction

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13
Q

What is self stimulation?

A

Animals will work to receive an electrical stimulus of certain brain areas

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14
Q

What areas are most effective for promoting self stimulation?

A

Ventral tegmental area

Median forebrain bundle (pathway between VTA and nucleus accumbens)

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15
Q

What other areas (to a lesser extent) will animals self stimulate?

A

Prefrontal cortex

Nucleus accumbens

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16
Q

What are the factors which influence self stimulation?

A

Drugs/ lesions

17
Q

What can be used to lesion areas containing tyrosine hydroxlase

A

6-OHDA

18
Q

What does 6-OHDA do when applied to NAc?

A

Blocks hyperactivity

19
Q

What is the effect on self stimulation on modification of applied current?

A

Self stimulation is not supported below a certain threshold

As the current increases so will press rate

20
Q

What occurs to press rate on lesions of the median forebrain bundle?

A

It will be abolished

21
Q

What will happen to press rate on self stimulation on low dose dopamine antagonists?

A

It will decrease i.e. Pressing lever will have a smaller effect therefore will not do as often

22
Q

What will happen to threshold current on addition of dopamine antagonists?

A

It will increase. I.e. Current which would normally support self stimulation will increase

23
Q

What is self administration?

A

Animals will work to receive drug infusions IV or intra cerebrally

24
Q

What drugs will be self administrated intravenously?

A 
Cocaine
Amphetamine
Ethanol
Morphine
Nicotine
25
Q

What drugs will be administered locally for promote self admin?

A

Amphetamine into the NAc

Morphine into the VTA

26
Q

What factors influence the self administration of cocaine and amphetamine?

A

Potentiated by dopamine antagonists i.e. Will work harder to overcome blockage of receptors @ low doses of antagonists. At high doses of antagonist all receptors will be block thus behaviour will be attenuated

27
Q

What else attenuates self administration?

A

6-OHDA lesions of the NAC

28
Q

What is conditioned place preference?

A

Rats will go to chamber where they receive a reward

29
Q

After condition get a particular chamber with a reward what will happen when a rat is placed into the chamber again? (Without reward)

A

Rat will go back to chamber where it received the reward. Can measure % time spent in either chamber (old reward chamber vs non reward chamber)

30
Q

What rewards will cause the rat to increase time spent in reward chamber?

A

Amphetamine
D1/D2 agonists
Food (amphetamine will enhance the reinforced behaviour)

31
Q

What other things can cause an increase in dopamine within the NAc?

A

Adverse stimuli e.g. Mild food shock

Release on stimuli predictive of either an adverse or rewarding stimuli

32
Q

What does dopamine increase in the NAc signal?

A

The salience of a stimuli. Useful for learning. For example, if you find food under a certain type of tree, seeing that tree will increase dopamine level and drive the motivation to eat. Like wise, if a certain see if predictive of a predator seeing that tree will elicit an increase in dopamine

33
Q

How do drugs effect dopamine?

A

Of the drugs a mouse will self administer all increase dopamine directly or indirectly (NAc>dorsal striatum)
All have addictive properties

34
Q

Why is it hypothesised that it is the potentiation of dopamine in the NAc which causes addiction?

A

The drugs all have different effects e.g. Some are stimulants, hallucinogens and others are depressants. Therefore, their addictive properties are unlikely to be related to their primary pharmacology but their ability to increase dopamine in the NAc

35
Q

what is a common property of addictive drugs?

A

Increase self stimulation
Support self administration
Show conditions place preference
Enhance reinforced behaviours

36
Q

What do addictive drugs do?

A

‘Hijack’ the physiological reward/salience pathway which signals if things are pleasurable or important. This system is essential for reinforcing behaviours of importance

37
Q

What can stimuli associated with drugs do?

A

Stimuli like watching another person take drugs or seeing a needle will make the person want to take the drug = dependency

38
Q

What are the signs and symptoms associated with dependency?

A 
Withdrawal
Interests (decrease)
Tolerance
Harmful consequences
Desire/compulsion
Control of intake decreases
39
Q

Overall wha tis the function of dopamine in the NAc?

A

Reinforce behaviours which are associated with pleasurable or adverse events through release of dopamine in response to salient stimuli

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