According to the Medilexicon’s Medical Dictionary,...

According to the Medilexicon’s Medical Dictionary, Addiction is â€Å"Habitual psychological or physiologic dependence on a substance or practice that is beyond voluntary control†(Nordqvist, 2009). This corresponds to the definition given by the current Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) that addiction is â€Å"When an individual persists in use of alcohol or other drugs despite problems related to use of the substance, substance dependence may be diagnosed. Compulsive and repetitive use may result in tolerance to the effect of the drug and withdrawal symptoms when use is reduced or stopped. This along with Substance Abuse are considered Substance Use Disorders† (Nordqvist, 2009). Addiction is generally held to be†¦show more content†¦It is shown that the brain experiences pleasure when the habit is repeated which leads to further and more regular use. Physical changes in nerve cells in the brain are the result of addictive abuse. These ‘nerve cells’ are also known as neurons, which release neurotransmitters into the synapses between nerve cells, which are then further received by receptors in other neurons. Put simply, a â€Å"neurotransmitter is a messenger of neurologic data from one cell to another cell† (Nordqvist, 2009). After time, the brain no longer experiences pleasure from a particular substance as the body as built up a tolerance to the substance, hence why experts warn that when tolerances to substances increase, so do the risk of addiction. Numerous scientists now believe that the brain is essentially a Bayesian hypothesis tester. One of it’s main roles is to make predictions regarding what input it expects to receive, following this, it updates these predictions in the light of the actual input. The brain attempts to minimize all prediction error and this kind of process takes place over many different levels of the processing hierarchy within the brain. The brain updates it’s predictions when expected inputs and actual input don’t correspond. It utilizes any divergence between expect and actual inputs to mold and generate its predictions shape. Other psychological processes can also be