explanations for nicotine addiction: brain neurochemistry Flashcards

1
Q

what is acetylcholine (ACh) ?

A

a neurotransmitter that plays a key role in attention, arousal, muscle movement, etc.

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2
Q

what is nAChR?

A

nicotinic acetylcholine receptor - a subtype of ACh receptor that can be activated either by ACh or nicotine

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3
Q

where can lots of ACh receptors be found?

A

on the surfaces of many neurons in CNS

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4
Q

what happens when nAChRs are activated by nicotine molecules?

A

the neuron transmits dopamine, which is immediately followed by shutdown of nAChRs

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5
Q

what is downregulation?

A

a reduction in the number of active neurons

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6
Q

what leads to downregulation?

A

desensitisation of neuron

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7
Q

where are nAChRs concentrated?

A

ventral tegmental area (VTA)

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8
Q

where is dopamine transmitted when nAChRs are stimulated by nicotine?

A

dopamine is transmitted along mesolimbic pathway to nucleus accumbens (NA), triggering release of more dopamine from NA to frontal cortex

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9
Q

what are the mesolimbic + mesocortical pathways part of?

A

the brain’s dopamine reward system

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10
Q

what does the activation of the dopamine reward system result in?

A

pleasurable effects (e.g. mild euphoria, increased alertness, etc.)

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11
Q

what happens when a person doesn’t smoke for a prolonged period (e.g. at night) ?

A

nicotine disappears from the body

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12
Q

what happens when nAChRs become functional again?

A

dopamine neurons resensitise and become more available (upregulation)

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13
Q

what happens during resensitisation?

A

nAChRs become overstimulated by ACh (as there’s no nicotine to bind with them)

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14
Q

why is the first cigarette of the day often the most enjoyable?

A

sensitive nAChRs reactivate the dopamine reward system

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15
Q

how does the smoker avoid unpleasant withdrawal symptoms?

A

by smoking another cigarette

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16
Q

what creates a long-term desensitisation of nAChRs?

A

the constant cycle of daytime downregulation + nighttime upregulation

17
Q

what does a continuous exposure of nAChRs to nicotine cause?

A

a decrease in number of active receptors, leading to tolerance development as a smoker needs more nicotine to get the same effects

18
Q

what are 2 strengths of this explanation?

A

~ research support
~ real-world application

19
Q

what are 2 limitations of this explanation?

A

~ it doesn’t fully explain withdrawal
~ biologically determinist

20
Q

what did McEvoy et. al. study?

A

smoking behaviour in people with schizophrenia who were taking an antipsychotic drug (which blocks dopamine receptors in the brain, therefore reducing dopamine transmission)

21
Q

what did McEvoy et. al. find?

A

people taking the drug showed a significant increase in smoking, presumably using it as a form of self-medication or to increase depleted dopamine levels

22
Q

what is one counterpoint to ‘research support’?

A

reductionist explanation - explanations that only consider dopamine are limited

23
Q

what did Watkins et. al. find as a counterpoint to McEvoy’s research?

A

nicotine addiction was also linked to GABA, serotonin, endogenous opioids etc. - therefore there is a complex interaction between several neurochemical systems

24
Q

how does this explanation have a real-world application?

A

knowledge of neurochemistry can lead to new treatments (e.g. NRT), showing that the explanation has validity

25
Q

how does nicotine replacement therapy (NRT) work?

A

a controlled dose of nicotine from products such as patches/gum acts neurochemically by binding with nAChRs + mimicking effects of nicotine from cigarettes

26
Q

true or false?:
this neurochemical explanation fully explains withdrawal

A

false - withdrawal effects can be explained in other ways without reference to amounts of nicotine

27
Q

what does Gilbert argue that?

A

withdrawal depends much more on environment + personality rather than amount of nicotine in the body

28
Q

what type of determinism is this explanation + why?

A

biologically determinist - this explanation suggests that nicotine is inevitable in someone who starts smoking