Researchers have discovered a new brain-circuit system in mice that sheds light on how the rodents transition from moderate to compulsive alcohol consumption -- an advance that may lead to the development of new approaches to study drug addiction in humans. The study, published in the journal Science, revealed that a nerve circuit in the mouse brain -- connecting the out layers in the cortex to the brainstem -- plays a key role in triggering compulsive drinking.
The researchers, including those from Vanderbilt University in the US, studied how the mouse brain is altered by binge drinking to drive compulsive alcohol consumption.
Based on the neural activity during the very first time the mice drank, the researchers said, they could predict which subjects would become compulsive.
Even when the subjects were given the same opportunity to drink, their behaviours deviated into distinct categories -- light, heavy and compulsive binge drinkers, they said.
They recreated a drinking scenario -- called a "binge-induced compulsion task" -- to assess how predisposition to binge drinking interacted with experience to produce compulsive behaviour.
The researchers tracked compulsive alcohol drinking during these first drinking experiences, and at later times.
They assessed the activity in the brains of the mice during the very first time the subjects drank alcohol using special imaging techniques and miniature microscopy.
The more active the neurons in the brains became, the less likely the subject would be to develop compulsive drinking behaviour, the study noted.
However, the neurons in drinkers predisposed for compulsive behaviour quieted during drinking events, they said.
According to the study, the neural activity differences were observed during the very first drinking experience, well before compulsive behaviours emerged.
This allowed the researchers to predict ahead of time which mice would become compulsive drinkers.
The research team said the biomarker and the behavioural model not only have implications on alcohol addiction studies but also on other substance abuse-related research.