Reward and drugs of abuse Flashcards

1
Q

Difference between rewarding and reinforcing?

A

Reward is a subjective term, reinforcing is objective

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2
Q

Which word is used in place of reward in animals?

A

Reinforcing

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3
Q

What are symptoms of psychological dependence?

A

Craving, compul drug use, loss of control

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4
Q

Symptoms of physical dependence?

A

When stopping a drug causes a withdrawal syndrome

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5
Q

What is tolerance?

A

When continued use of a drug results in the need for increasing doses for equivalent effect

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6
Q

Who first discovered brain sites where direct electrical stimulation is reinforcing?

A

Olds and Milner

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7
Q

How did Olds and Milner discover reinforcing brian sites?

A

Implanted electrodes into different parts of rat brains, Rat was in charge of which parts were stimulated–> idea was that theyd stimulate the reinforcing parts

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8
Q

What is the mesolimbic pathway?

A

The reward pathway

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9
Q

How were the NTs involved in the mesolimbic pathway determined?

A

Microdialysis

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10
Q

How does microdialysis work?

A

Probe is inserted into brain region (tip of probe has dialysis tubing)–> NT that is released from nerve terminals that are where the probe is will enter the tip–> contents are pumped out

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11
Q

Why is dialysis tubing used in NT determination?

A

It has a semi-permeable membrane

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12
Q

What machine is the solution, acquired as a result of microdialysis, pumped into?

A

HLPC

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13
Q

Which NT is involved in reward?

A

Dopamine

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14
Q

Where are the dopaminergic neurones projecting from and to in the mesolimbic pathway?

A

From the ventral tegmental area to the nucleus accumbens

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15
Q

How does self administration work?

A

Cannula is implanted into the brain–> anything that is put into the cannula will go straight into the brain, animal can control this

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16
Q

What is the effect of 6-hydroxydopamine?

A

It is toxic but only to dopaminergic neurons

17
Q

What happens to animals self-administration of drugs if dopaminergic pathways in the brain are lesioned?

A

They don’t self administer anymore

18
Q

What is lesioning a brain pathway?

A

Using a chemical to turn that pathway off

19
Q

What happens to animals self-administration of drugs if dopamine D1 or D2 antagonists are used?

A

They wont self administer anymore

20
Q

What does an increase of dopamine in the nucleus accumbens feel like?

21
Q

What does an decrease of dopamine in the nucleus accumbens feel like?

22
Q

What was the effect of most drugs of abuse on the amount of dopamine in the nucleus accumbens?

A

They increased it

23
Q

Why is it thought that rodents take diazepam?

A

Reduces their anxiety

24
Q

How do cocaine and amphetamine increase dopamine levels in the nucleus accumbens?

A

They are both dopamine reuptake inhibitors

25
What can amphetamine do that cocaine cant?
Directly cause dopamine release
26
How is it thought that amphetamine causes dopamine release?
It allows reverse transport through the transporters that usually allow dopamine back into the presynaptic neuron
27
How do opioids increase the levels of dopamine in the nucleus accumbens?
Inhibit the GABA neurons that would otherwise inhibit the dopaminergic neurons in the ventral tegmental area
28
How does ethanol increase the amount of dopamine in the nucleus accumbens?
Close K+ channels on the postsynaptic neurons in NA, decreasing hyperpolarisation post one AP meaning APs will fire more frequently
29
Which class of drugs does ethanol have a similar effect to regarding GABAa receptors?
Benzodiazepines--> it is an allosteric modulator (anxiolytic)
30
How does nicotine increase dopamine levels in nucleus accumbens?
Nicotine acts on nicotinic ACh receptors on dopaminergic neurons in the VTA, increasing the firing rate so more dopamine is released
31
How does THC increase dopamine levels in nucleus accumbens?
Acts on cannabinoid receptors which are on GABAergic interneurons--> GI/GO coupled GPCRs--> causes inhibition of the GABAergic neuron so less inhibitory GABA is sent to the dopaminergic neurons in the VTA
32