New light shed on how memory is organised

  A method that allowed measurements right down to the millisecond level was used

In an article published  in Nature, researchers describe exactly how the brain reacts during the transition between one memory and the next.

Consider these situations: You're rudely awakened by the phone. Your room is pitch black.

It's unsettling, because you're a little uncertain about where you are — and then you remember. You're in a hotel room.

Similar disorientation

Sound like a familiar experience? Or maybe you've felt a similar kind of disorientation when you walk out of an elevator onto the wrong floor?

But what actually happens inside your head when you experience moments like these?

The study by researchers at the Norwegian University of Science and Technology's Kavli Institute for Systems Neuroscience employed a method that allowed them to make measurements right down to the millisecond level.

The research was conducted in the laboratory of May-Britt and Edvard Moser, co-director and director respectively of NTNU's Kavli Institute, by first author Karel Jezek.

Their findings show that memory is divided into discrete individual packets, analogous to the way that light is divided up into individual bits called quanta. Each memory is just 125 milliseconds long — which means the brain can swap between different memories as often as eight times in one second, according to a Norwegian University of Science and Technology press release.

“The brain won't let itself get confused,” says Professor May-Britt Moser. “It never mixes different places and memories together, even though you might perceive it that way.

This is because the processes taking place inside your head when your brain is looking for a map of where you are take place so fast that you don't notice that you are actually switching between different maps. When you feel a little confused, it is because there is a competition in your brain between two memories. Or maybe more than two.”

Brain researchers Edvard and May-Britt Moser are trying to understand exactly how the brain works. Their approach is to meticulously monitor electrical activity in different parts of the rat brain, while the rats explore different mazes.

Painstaking approach

It's a painstaking approach that provides them ever more pieces to the puzzle that is the workings of the brain.

To explore the question of whether the brain mixes memories together, the researchers created a special box for their laboratory animals that effectively enabled them to instantaneously ‘teleport' a rat from one place to another — without the help of the Starship Enterprise as featured in the science fiction teleseries ‘Star Trek.'

Then, they tested how the brain handled the memory of place when the experience of that place suddenly changed from one location to another.

“We tricked the rats,” May-Britt Moser explains. “They're not really teleported of course, but we have an approach that makes them believe that they have been. The features of the box, which give the rats a sense of where they are, are actually ‘constructed' out of different lighting schemes. So we can switch from one group of location characteristics to another with the flick of a light switch.