According to "Psychology Today," although there are over 4,000 chemicals in cigarettes, it is mainly the nicotine that is affecting the brain. It does this just like drugs do. Quite rapidly, a person becomes addicted to nicotine, then builds tolerance to it, and finally, should a person decide to stop smoking, he will experience withdrawal symptoms. Many brain areas and neurotransmitters are responsible for this circle of addiction.
Reward Pathway and Dopamine
According to the National Institute on Drug Abuse, nicotine is carried from the lungs to the brain in 10 to 15 seconds. There nicotine binds to nicotine receptors that are located in the ventral tegmental area of the brain that is also called the VTA. This area, located in the midbrain, is part of the so-called reward pathway. The other parts of the reward pathway are the nucleus accumbens and the prefrontal cortex. This pathway is made up of neurons that release neurotransmitters called dopamine when they are stimulated. Nicotine increases the rate at which dopamine is released, causing an intense feeling of pleasure.
Prefrontal Cortex
Many smokers claim that they are able to concentrate better if they smoke. This is likely to be caused by the effects that nicotine has on the prefrontal cortex. Nicotine increases the release of glutamate, a neurotransmitter found in the prefrontal cortex. It is this activation that enhances concentration and memory, concluded Dr. Evelyn K. Lambe and colleagues in a 2003 study that was published in volume 23 of the journal "Neuropsychopharmacology."
Insula
The insula is located in the cerebral cortex between the temporal and the frontal lobes. This area of the brain is responsible for making a person aware of sensations in the body, such as pain or hunger. This makes plausible that the insula might also play a role in reminding a smoker of the good feeling received after smoking. This area might also make an addict remember cues associated with smoking, such as commercial breaks on TV.
Dr. Nasir Naqvi and colleagues studied whether damage to the insula might make a person stop smoking. They found that 68 percent of the subjects who had an injury in the insula stopped smoking right after the damage occurred, did not start smoking again and reported that it was remarkably easy for them to quit. This furthers the idea that the insula seems to play a major part in the awareness a person has of the discomfort experienced during withdrawal and remembering the positive feelings associated with smoking. These findings were initially published in the journal "Science" in January 2007.
