effect of recreational drugs on neurotransmission

Question 1

what are the 2 reward pathways in the brain?

Answer 1

• mesolimbic
• mesocortical

Question 2

describe the mesolimbic reward pathway?

Answer 2

• starts in the ventral tegmental area (VTA)
• which is connected to the nucleus accumbens
• which is associated with motivation and reward

Question 3

describe the mesocortical reward pathway?

Answer 3

• starts in the ventral tegmental area (VTA)
• but travels to the cerebral cortex

Question 4

cocaine

Answer 4

• addictive stimulant drug
• which hijacks the feel good network in the brain
• it blocks the bindings sites of the re-uptake receptors on the presynaptic neurone
• so there is excess dopamine in the synapse
• that leads to the overstimulation of the dopamine receptors on the post synaptic neurone
• the increase in dopamine is what causes the initial euphoria
• many people become dependent on the drug as the overstimulation of the dopamine receptors causes them to become damaged and decrease in number
• leading to desensitisation and addiction

Question 5

nicotine

Answer 5

• stimulant drug
• which affects the CNS and peripheral NS
• it speeds up messages travelling between the brain and the body
• it works on the mesolimbic reward pathway
• it mimics the action of acetylcholine as it has a similar shape so can fit into the dopamine receptors on the post synaptic neurone to cause similar feelings of pleasure
• overtime the overstimulation of the dopamine receptors causes a decrease in their number and a change in the shape of the cell
• when no nicotine is present more dopamine is needed to stimulate the post synaptic neurone leading to desensitisation and addiction

Question 6

strengths

Answer 6

Supporting evidence from researchers who lesioned the mesolimbic reward pathway in mice to prevent the production of dopamine when associated with reward. This caused mice to not self administer cocaine intravenously, but this did not occur when different brain parts were lesioned. Therefore, showing how the effects of cocaine are directly due to the activity of dopamine in the mesolimbic reward pathway.

Supporting evidence from Olds and Milner who placed electrodes into different areas of rats brains and put them into a skinner box. They found the rats would self stimulate themselves by pressing on the lever, especially if the stimulation was in the VTA. Therefore, suggesting that there are various brain areas where stimulation is rewarding enough for animals will stimulate themselves frequently and regularly overtime. Meaning they may be experiencing reward due to dopamine production.

• animal research. as the results of if rats would stimulate themselves in certain brain areas are not representative of humans stimulating themselves for feelings of pleasure from dopamine using drugs. low gen.

Question 7

weaknesses

Answer 7

An alternative explanation could be the learning theories. For example, it suggests that people become classically conditioned to use drugs as drugs are associated with popularity so end up eliciting a response of pleasure. Therefore, people may take drugs and become addicted associating them with things, so the biological explanation of how drugs impact neurotransmission is reductionist as it doesn’t explain why people start doing drugs in the first place.

Question 8

application

Answer 8

High application to society as having a clear understanding of how recreational drugs can affect the CNS functioning may lead to better treatments for addiction and help discover more effective ways of preventing it. Therefore, drugs that have a reverse effect can be made to help those suffering with depression and addiction.