Addicted to...

Nicotine affects the same parts of the brain as cocaine on first exposure, according to a study published in The Journal of Neuroscience. A single 15-minute exposure to nicotine caused a long-term increase in the excitability of neurons involved in reward, in a similar manner to cocaine. The finding suggests that memory-like effects in the brain's reward pathway could contribute to drug addiction. Danyan Mao of the University of Chicago Medical Center points out that, "for smoking it's a very long-term behavioral change, but everything starts from the first exposure."