Compared to adults, kids learn fast, their developing brains sopping up information at a mind-boggling pace. Somehow their neurons not only incorporate new knowledge more easily, they hold onto it firmly, even in a constant torrent of new experiences.

Now, a team of neuroscientists from the University of Regensburg in Germany and Brown University in the US may have discovered what makes young brains so efficient.

It's all down to a brain chemical known as GABA (gamma-aminobutyric acid) which surges in children during and after learning, turning their young brains into 'uber-sponges'.

"It's often assumed that children learn more efficiently than adults, although the scientific support for this assumption has, at best, been weak," says study co-author Takeo Watanabe, a cognitive psychologist from Brown University.

Searching for the brain mechanisms involved, the team used an advanced neuroimaging technique called functional MRS (fMRS) to indirectly measure concentrations of GABA in the visual cortex of kids during a visual learning activity to see how it differed from adults.

Measurements were taken in 55 children aged 8 to 11 years and 56 adults aged between 18 and 35 years of age, covering three different periods: before the visual learning task began, during the learning process, and after the activity had ended.

The results showed that GABA levels in adults remain consistent over the whole experiment. Meanwhile, the GABA levels in children were much more adventurous.

"What we found is a rapid increase in GABA in children, associated with learning," says Watanabe. And not just during learning – the high levels of GABA lasted into the post-learning period too.

It's a revelatory finding, Watanabe says.

GABA is a chemical messenger in the brain known to be important in the process of learning new information. It also plays a key role in stabilization, a 'cooling-off period' after learning whereby the fragile new neural networks are consolidated and the information successfully stored.

But if something new is learned during the cooling-off period, a phenomenon called 'retrograde interference' kicks in, where the previously learned information is overridden or destroyed – it slips out of our brains.

Think of it as like leaving a pie to cool off after it's been taken from the oven. Resting it gives the starches in the filling a chance to set into a gel that will hold everything neatly in place. If you cut into the pie during cooling period, though, the piping hot filling is runny and spills out.

With the new knowledge of GABA levels in kids on board, the team then conducted behavioral experiments to see if this was what allowed visual learning to be stabilized more rapidly. What they found was astonishing.

Adults needed a 'cooling off period' of an hour to allow for stabilization. However, the children were able to learn again within 10 minutes without overriding what they had previously learnt. In other words, thanks to their lofty GABA levels, their pie sets a whole lot quicker.

"We found that resilience to retrograde interference and therefore stabilization indeed occurred within minutes after training ended in children, whereas learning was in a fragile state in adults for at least one hour after training," the researchers wrote in their paper.

"This rapid stabilization of learning in children enables them to learn more items within a given period of time and makes learning more efficient in children than adults," explains psychologist and cognitive neuroscientist Sebastian Frank, a co-author on the study now at the University of Regensburg in Germany.

The researchers also found consecutive sessions of learning seemed to further increase the GABA concentration in children, allowing even more rapid stabilization of previous learning.

"Our results therefore point to GABA as a key player in making learning efficient in children," says Frank.

While it should be noted that this study was done in visual learning, Watanabe believes these findings could be generalized to other types of learning involving memory.

Excitingly, these findings could be used to help adults learn more efficiently.

"For example, a new technology or therapy could be developed to increase the amount of GABA in the brains of adults," Watanabe says. "That is one possible application."

This research was published in Current Biology.