The Natural Reward System for the Brain
Neurons are cells directly responsible for passing chemical and electrical signals down and along the pathways of the brain, and each neuron has special functions like storing memory and/or controlling our muscles.
In the center of the brain lies the reward pathway, which drives our feelings of motivation, behavior and reward.
Drugs Alter the Brains Reward Pathway
Drugs bypass the five senses and directly enter and activate the brain's reward circuitry, this is how drugs can cause a quick jolt of pleasure. The abuse of drugs can affect the brain in such a huge way that the brain will start to try to adapt. One way the brain adapts is to lower the number of dopamine receptors at the synapse, this will lead to the user needing more of the drug the next time they want to get high.
As the brain continues to get used to the presence of the drug, areas outside of the reward pathway will also start to be affected. Brain regions that are used for things like learning judgement and memory can start to physically change. Once this happens, drug seeking behavior becomes a very hard to break habit, which in turn leads to the so called "Drug Addict". Drugs can affect the brain and the body so much that an overly large dose can actually kill the person using the drug.
