A radio metaphor


ScienceDaily has a report (here) on research by L. Colgin and group as published in Nature.

Colgin and her colleagues measured brain waves in rats, in three different parts of the hippocampus, which is a key memory center in the brain. While listening in on the rat brain wave transmissions, the researchers started to realize 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,” she says. …

“When brain cells want to connect with each other, they synchronize their activity. 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.”…

“The cells can rapidly switch their activity to tune in to the slow waves or the fast waves,” Colgin says, “but it seems as though they cannot listen to both at the exact same time. This is like when you are listening to your radio and you tune in to a frequency that is midway between two stations- you can’t understand anything- it’s just noise.”…

“This switch mechanism points to superfast routing as a general mode of information handling in the brain,” says Edvard Moser, Kavli Institute for Systems Neuroscience director. “The classical view has been that signaling inside the brain is hardwired, subject to changes caused by modification of connections between neurons. Our results suggest that the brain is a lot more flexible. Among the thousands of inputs to a given brain cell, the cell can choose to listen to some and ignore the rest and the selection of inputs is changing all the time. We believe that the gamma switch is a general principle of the brain, employed throughout the brain to enhance interregional communication.”

It looks like there may be yet another dimension to communication in the brain.

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