One of the most important parts of the brain is the “executive centre”, right at the front. It’s the area that gathers information in order to make effective decisions, and to plan.

It’s fiendishly clever.

So, when we pause to think before making an important decision, we may imagine the various outcomes of the different choices we could make.

While this “mental simulation” is central to how we plan and make decisions in everyday life, how does the brain do it?

Led by Cambridge University, an international team of scientists have come up with a mechanism using an interplay between the brain’s prefrontal cortex and the hippocampus, which allows us to imagine future outcomes to guide our decisions.

“The prefrontal cortex acts as a ‘simulator’, mentally testing out possible actions using a cognitive map stored in the hippocampus,” says co-author Marcelo Mattar from New York University.

The roles of both the prefrontal cortex – used in planning and decision-making – and hippocampus – used in memory formation and storage – have long been established. However, their specific duties in making decisions that require us to think before acting have been elusive.

To illuminate the brain mechanisms of planning, Mattar and his colleagues, Kristopher Jensen, University College London, and Professor Guillaume Hennequin, Cambridge, developed computer modelling to predict brain activity during planning.

The model takes into account existing knowledge of planning and adds new layers of complexity, including “imagined actions”, thereby capturing how decision-making weighs up the impact of potential choices – similar to how a chess player envisions sequences of moves before committing to one.

These mental pictures of potential fallout, through interactions between the prefrontal cortex and hippocampus, enable us to adapt rapidly to new environments, such as taking a detour after finding a road is blocked.

The scientists validated this model using both behavioural and brain data.

To assess the model’s ability to predict behaviour, subjects navigated an online maze on a computer screen and how long they had to think before each step was measured.

To study the role of the hippocampus in planning, researchers drew parallels between behavioural and neural data.

“Allowing neural networks to decide for themselves when to ‘pause and think’ was a great idea, and it was surprising to see that in situations where humans spend time pondering what to do next, so do these neural networks,” said Hennequin.

“This new framework will enable systematic studies of thinking at the neural level,” said Hennequin.

“This will require a concerted effort from neurophysiologists and theorists, and I’m excited about the discoveries that lie ahead.”

Great news.