The effect of recreational drugs

• What are recreational drugs?

  Drugs that are taken, in the absence of medical grounds, for personal enjoyment. Often referred to as 'psychoactive' drugs as they alter our brain function which changes our mood and perception of conscious experience.
• What is the mesolimbic pathway?

  A reward pathway, in the brain, that operates on the neurotransmitter dopamine which causes us to experience pleasant and rewarding feelings.
• Reward pathways

  • Behaving in a certain wa can activate reward pathways.
  • This encourages the behaviour to be repeated (to feel pleasant and rewarding behaviour).
  • Recreational drugs can hijack the reward system.
• Cocaine's mode of action

  • Has a stimulant effect in the CNS, especially the neurons of the mesolimbic pathway.
  • The drug achieves its affects by altering synaptic transmission.
  • Like all recreational drugs, it increases dopamine release.
  • Cocaine blocks reuptake of dopamine by binding with dopamine transporter molecules on the terminal buttons of the presynaptic neuron.
  • This causes the synapse to be flooded with surplus dopamine.
  • After repeated cocaine use, dopamine receptors become downregulated meaning the production of dopamine declines (the drugs is required for dopamine production).
• Evaluation

  • Research using animals - deliberately damaging the mesolimbic pathway in mice causes the neurons to be unable to produce levels of dopamine normally, mice then fail to self-administer cocaine intravenously.
  • This does not happen in other parts of the mice's brain therefore supporting the view that cocaines effects are due to the activity of dopamine in the brains reward system.
• Evaluation

  • The basic transmission process' in animals are similar to humans but some differences arise because the human brain is more complex than a mouse brain. Therefore, it's difficult to generalise the evidence to humans.
  • Isolating the effects of just one neurotransmitter oversimplifies the process.
• Evaluation

  • (Application) - as knowledge of drugs on CNS transmission grow, more treatment for addiction becomes available.