New York, March 13 (IANS): Despite umpteen resolutions that you are going to quit smoking, why do you succumb the very next day to that uncontrollable craving to light another one?

Blame it on the weakened brain connections that are tied to self-control over cigarette cravings.

A new brain imaging study from scientists at University of Pennsylvania and the National Institute on Drug Abuse (NIDA) shows how smokers suffering from nicotine withdrawal may have more trouble shifting from a key brain network.

Moving from default mode, when people are in a so-called 'introspective' state, into a control network that could help exert more conscious, self-control over cravings and to focus on quitting for good has now been understood.

“The findings help validate a neurobiological basis behind why so many people trying to quit end up relapsing and may lead to new ways to identify smokers at high risk for relapse who need more intensive smoking cessation therapy,” explained Caryn Lerman, deputy director of Penn's Abramson Cancer Centre.

The researchers found that smokers who abstained from cigarettes showed weakened inter-connectivity between certain large-scale networks in their brains - the default mode network, the executive control network, and the salience network.

This weakened connectivity reduces smokers' ability to shift into or maintain greater influence from the executive control network which may ultimately help maintain their quitting attempt.

“What we believe this means is that smokers who just quit have a more difficult time shifting gears from inward thoughts about how they feel to an outward focus on the tasks at hand,” Lerman added.

It is very important for people who are trying to quit to be able to maintain activity within the control network - to be able to shift from thinking about yourself and your inner state to focus on your more immediate goals and plan, suggested Elliot Stein from NIDA.

For the study, researchers conducted brain scans on 37 healthy smokers (those who smoke more than 10 cigarettes a day) aged 19 to 61 using functional magnetic resonance imaging (fMRI) in two different sessions.

Imaging showed a significantly weaker connectivity between the salience network and default mode network during abstinence.

The weakened connectivity during abstinence was linked with increases in smoking urges, negative mood and withdrawal symptoms - suggesting that this weaker inter-network connectivity may make it more difficult for people to quit.

The next step is to identify in advance those smokers who would have more difficultly quitting and target more intensive treatments, based on brain activity and network connectivity, said the study, published in the journal JAMA Psychiatry.