How does the brain zero in on a single bit of information, out of the tens of thousands that it is bombarded with daily? Researchers at the Norwegian University of Science and Technology (NTNU), have discovered a mechanism that the brain uses to filter out distracting thoughts to focus on a single bit of information.

Think of your brain like a radio: You’re turning the knob on to find your favourite station, but the knob jams, and you’re stuck listening to something that’s in between stations.

It’s a frustrating combination that makes it quite hard to get an update on swine flu while a Michael Jackson song wavers in and out. Staying on the right frequency is the only way to really hear what you’re after.

In much the same way, the brain’s nerve cells are able to “tune in” to the right station to get exactly the information they need, says Laura Colgin of the NTNU, who led the research.

Just like radio stations play songs and news on different frequencies, the brain uses different frequencies of waves to send different kinds of information,” she says.

“You know how when you feel like you really connect with someone, you say you are on the same wavelength? When brain cells want to connect with each other, they synchronise their activity,” Colgin explains.

Colgin and her colleagues measured brain waves in rats, in three different parts of the hippocampus, which is a key memory centre.

While listening in on the rat brain wave transmissions, the researchers started to realise that there might be something more to a specific sub-set of brain waves, called gamma waves.

Researchers have thought these waves are linked to the formation of consciousness, but no one really knew why their frequency differed so much from one region to another and from one moment to the next.

Information is carried on top of gamma waves, just like songs are carried by radio waves. These “carrier waves” transmit information from one brain region to another.

“We found that there are slow gamma waves and fast gamma waves coming from different brain areas, just like radio stations transmit on different frequencies,” Colgin says, according to an NTNU release.

“The cells literally tune into each other’s wavelength. We investigated how gamma waves in particular were involved in communication across cell groups in the hippocampus.”

“What we found could be described as a radio-like system inside the brain. The lower frequencies are used to transmit memories of past experiences, and the higher frequencies are used to convey what is happening where you are right now.”

These results were published in the November issue of Nature.

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