Nicotine is a nitrogen-containing chemical – an alkaloid, which is made by several types of plants, including the tobacco plant. Nicotine is also produced synthetically. Nicotiana tabacum, the type of nicotine found in tobacco plants, comes from the nightshade family. Red peppers, eggplant, tomatoes and potatoes are examples of the nightshade family. Apart from being a substance found in tobacco products, nicotine is also an antiherbivore chemical, specifically for the elimination of insects – it used to be extensively used as an insecticide.
When humans, mammals and most other types of animals are exposed to nicotine, it increases their heart rate, heart muscle oxygen consumption rate, and heart stroke volume – these are known as pharmacologic effects. The consumption of nicotine is also linked to raised alertness, euphoria, and a sensation of being relaxed. At the same time, nicotine is highly addictive. People who are regularly exposed to nicotine and then suddenly stop experience withdrawal symptoms, which may include cravings, a sense of emptiness, anxiety, depression, moodiness, irritability, and inattentiveness.
With recent studies, researchers have determined an aspect of brain activity which might just help explain why for some tobacco smokers, strategies to aid quitting smoking work great, while for many others no method seems to work.
Scientists from Penn State looked at the brains of nicotine-deprived smokers with functional magnetic resonance imaging (fMRI) and noticed that those who exhibited the weakest response to rewards were also the least willing to stop smoking, even when offered money as an alternative. ‘We believe that our findings may help to explain why some smokers find it so difficult to quit smoking,’ said Stephen J Wilson, assistant professor of psychology.
‘Namely, potential sources of reinforcement for giving up smoking – for example, the prospect of saving money or improving health – may hold less value for some individuals and, accordingly, have less impact on their behaviour, he added.
The scientists invited 44 smokers to examine striatal response to monetary reward in those expecting to smoke and in those who were not, and the following willingness of the smokers to refuse a tobacco cigarette in an effort to earn more quick money.
‘The striatum is part of the so-called reward system in the brain. It is the area of the brain that is important for motivation and goal-directed behavior – functions highly relevant to addiction,’ said Wilson.
All of the people in the study, who were between the ages of 18 and 45, said that they smoked at least 10 cigarettes every day in the past year. They were told to cease smoking and stop using any alternative products containing nicotine for 12 hours before the experiment took place.
During a card-guessing task, half of the attendants were told that there had been a mistake, and they would be allowed to smoke during the 50-minute break that would occur after 16 minutes. But, after the minutes passed, the smoker was told that for every 5 minutes without cigarettes he or she would receive USD 1 – with the potential to earn up to USD 10.
Scientists eventually found that smokers who could not resist the temptation to smoke also showed weaker responses in the ventral striatum when offered monetary rewards while in the fM