but in the reward center of the brain, the two substances have a similar effect. According to a study conducted by the University of Chicago Medical Center, a single 15-minute first exposure to nicotine can trigger a memorylike response from dopamine — a neurotransmitter active in processing addictive drugs as well as natural rewards such as food. Researchers found that the brain records the effect of the nicotine and creates long-term changes in the brain, which make it difficult to quit.