Smokers could be predisposed to the habit because of the make-up of their brains, research suggests.

The behavior of molecules produced at the synapse connection points between nerve cells could make them more likely to smoke cigarettes.

And the discovery could also have wider implications for understanding the molecular basis of other aspects of human thought.

Scientists found the smoking link after developing a new brain map which helps explain why certain behaviors are linked to particular areas of the brain.

A team from the University of Edinburgh found the pattern of molecules varied between areas of the brain and these differences correspond to functions including language, emotion and memory.

Study lead Professor Seth Grant added: “We have been able to bridge the gap between what’s known about the genetics of smoking on one hand, and what’s known about which part of the brain smoking behavior is controlled in.”

“What it appears to be is that the propensity to smoke is influenced by the molecular composition of your brain in that particular part of your brain.”

Synapses play a critical role in controlling different aspects of behavior, the scientists explained, so understanding them can shed light on the functions of particular brain regions.

The brain maps could help new treatments for different conditions target certain parts of the brain.

Grant added: “Those molecules, synapses, which connect nerve cells together are very important in controlling behavior.”

“One of the aspects of our study was to relate the molecular composition of part of the brain to many different other kinds of behavior — language areas, emotional areas, memory and so on.”

“This will help us to get new treatments to certain parts of the brain.”

Researchers said that analyzing the molecular make-up of synapses in this way provided a snapshot of the genes that are expressed in different areas of the brain.

Using their new map, they were able to investigate where genes that have been linked to smoking exert their influences on the brain.

The findings pinpointed the same region that has previously been identified in brain imaging studies.

This confirms that the map can bridge the gap between genetic studies and findings from brain imaging to help to explain how the brain works, according to the scientists.

They say the new map provides a powerful tool for investigating how diseases affect different parts of the brain.

The researchers have now made all of their data available to help further research.

The study, published in Nature Neuroscience, was based on postmortem brain tissue samples from healthy people held in the Medical Research Council’s Edinburgh Brain Bank.

Grant added: “This is an important step toward understanding the molecular basis of human thought.”

Dr. Kate Adcock, the Medical Research Council’s Head of Neurosciences and Mental Health, said: “This innovative study enriches our understanding of the human brain through its use of samples from the Medical Research Council’s Edinburgh Brain Bank.

“The information that Professor Grant and his team has generated provide an excellent opportunity for researchers to gain further insight into how the brain works.”