effect of recreational drugs on transmission

• o   Recreational drugs are those used in the absence of medical grounds, for personal enjoyment.

  o   Referred to as psychoactive drugs as they alter the brain functions which changed mood and perception.

  o   They act by changing the way neurotransmitters work in the brain.
• o   Most psychoactive drugs work on the dopamine system which increases the release of dopamine in the reward pathway, causing the person to feel an extreme high and euphoria.

  o   However, over time, this causes the brain to produce less dopamine (down regulation of dopamine) so when the effects from the drug wear off there would be less dopamine in their system than what they would’ve had before taking the drug so now the person would feel an extreme low and dysphoria making them want to take the drug again to reproduce that euphoric feeling.
• Repeated use of the drugs causes a further down regulation of dopamine making the person physically dependent on the drug to avoid any other feelings of withdrawal so leads to addiction.
• alcohol - GABA is released, is an inhibitory neurotransmitter therefore making it less likely for the next neurone to fire. Alcohol causes an enhanced effect of GABA which results in CNS depression.

  Has a depressant effect on the nervous system by increasing the action of GABA.
• cocaine - Inhibits reuptake therefore increased levels of dopamine between the synapses.
• nicotine - Mimics acetylcholine and enters the blood when inhaled and attached to acetylcholine receptors causing an increased release of dopamine in the reward pathway producing a feeling of pleasure.
• heroin - Strongly activate the dopamine neurones and only excited the serotonin receptors on high doses. The brain decreases how much dopamine and serotonin it releases as it is already by added to the bloodstream artificially so when the effect wears off, the brain will still release less dopamine causing the person to feel extreme dysphoria.

  (Heroine increases the amount of dopamine in the reward pathways of the brain by boosting the activation of dopamine synapses, causing an intensely pleasurable experience, or feeling of euphoria. )
• There is a lot of evidence supporting the suggestion that recreational drugs affect transmission. Olds and Milner (1954) found a pleasure centre in the brain of rats. Straiker et al (2012) looked at the effect of cannabis and found an effect in the hippocampus of mice. This is reliable research, with very careful controls. However, we must be cautious in making generalisations from animal studies to humans due to the vast differences in brain structures particularly in the cortical area (e.g., the pre-frontal cortex).
• There is a complexity in how transmission works in the brain that is hard to capture. Current tools cannot measure transmission. Cannabis limits hippocampal activity, but also leads to more dopamine activity and there is more than one reward pathway. Having one explanation for the mode of action of a recreational drug seems rather simplistic.