Nicotine plays tricks on brain

Researchers have found that nicotine, the addictive component in cigarettes, "tricks" the brain into creating memory associations between environmental cues and smoking behaviour. This could help explain why former smokers miss lighting up when they are in a bar or after a meal.

The findings from researchers at Baylor College of Medicine are in journal Neuron.

"Our brains normally make these associations between things that support our existence and environmental cues so that we conduct behaviours leading to successful lives. The brain sends a reward signal when we act in a way that contributes to our well being," study co-author Dr John A. Dani, professor of neuroscience at BCM said. "However, nicotine commandeers this subconscious learning process in the brain so we begin to behave as though smoking is a positive action."

Dani said that environmental events linked with smoking can become cues that prompt the smoking urge. Those cues could include alcohol, a meal with friends or even the drive home from work.

Dani and Dr Jianrong Tang, instructor of neuroscience at BCM and co-author of the report, recorded the brain activity of mice as they were exposed to nicotine.

How the study was done
The mice were allowed to roam through an apparatus with two compartments. In one compartment, they received nicotine. In the other, they got a saline solution. The researchers recorded how long the mice spent in each compartment and brain activity within the hippocampus, an area of the brain that creates new memories.

"The brain activity change was just amazing," Dani said. "Compared to injections of saline, nicotine strengthened neuronal connections -- sometimes up to 200%. This strengthening of connections underlies new memory formation."

Dani said understanding mechanisms that create memory could have implications in future research and treatments for memory disorders, such as Alzheimer's disease, and for dopamine signalling disorders, such as Parkinson's disease. – (HealthDay News, September 2009)

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