the effect of recreational drugs

Question 1

what are recreational drugs?

Answer 1

• drugs that are taken by users for personal enjoyment.
• they alter brain function, which changes our mood, perception of conscious experience.
• examples: caffeine, nicotine, alcohol, cocaine, heroin

Question 2

what is the reward pathway in the brain?

Answer 2

• the most important reward pathway in the brain is the mesolimbic pathway. this operates on the neurotransmitter dopamine. the release of dopamine in the pathway causes us to experience pleasant and rewarding feelings.
• the reward pathway has an adaptive function because if we behave in a certain way which leads to the activation of this pathways then this encourages us to repeat the behaviour again.

Question 3

what is the problem with recreational drugs and the reward pathway?

Answer 3

• the drugs hijack this reward system. they produce pleasurable feelings without having any adaptive value.

Question 4

addiction and maintenance of addiction

Answer 4

eg. if a person is addicted to heroin,
1 this recreational drug hijacks the reward system and this is not an involved response.
2 the first time the person takes the heroin dopamine is increased and then that imitates the reward pathway.
3 the brain then naturally reduces dopamine, so we now need more when it wears off.
4 person takes another hit to increase the feeling of pleasure and reward but brain reduces dopamine again.
5 without the drug the brain needs more reward.

Question 5

the effect of transmission of drugs on the CNS

Answer 5

• there are 3 ways that drugs interfere with the processes at the synapse.
  1 block receptors so that neurotransmitters can’t fit into them.
  2 attach to receptors and mimic the effect of neurotransmitters.
  3 prevent recycling of neurotransmitters so that they stay in the synapse and reattach to receptor cells.

example: cocaine
blocks binding site of reuptake causing excess dopamine in the synapse leading to overstimulation on receptor sites.
this effect eventually damages the receptor sites reducing the amount meaning more coin is needed to maintain a normal level.

• dopamine is important in the development of addiction.

Question 6

evidence

Answer 6

research using animals - deliberately damaging the mesocorticolimbic pathway in the brains of mice.
- neurone are unable to produce levels of dopamine normally associated with reward. mice then fail to self administer coaine intravenously - this does not occur in other parts of mice brain when performed.
- this supports the view that cocaines effect are due to activity of dopamine in brains reward system.

Question 7

CA

Answer 7

• even tho the basic transmission process is similar in animals and humans, some differences arise because the human brain is more complex than the mouse brain, making it difficult to generalise the effects to humans. also isolating the effects of just one neurotransmitter oversimplifies the process.