http://www.newscientist.com/article/mg15621052.800-radio-head--the-brain-has-its-own-fm-receiver.html
Seven years ago, they found that a monkey's cortex has certain neurons that continuously oscillate. "It was not at all clear what their role might be," says Ahissar.
His team decided to study rats to see if these oscillations have a role in sensory perception. Rats find out about objects around them by touching them with quivering whiskers.
The researchers monitored neurons in the cortex that receive information from whiskers. They found that even when the rats were not moving their whiskers or touching anything, a tenth of the neurons had an intrinsic frequency of about 10 hertz. When the whiskers touch an object, the frequency of the neuron oscillation alters.
This means that the brain interprets the signals like an FM radio, says Ahissar in the current issue of Proceedings of the National Academy of Sciences (vol 94, p 11633). Frequency modulation (FM) transmitters send out a "carrier" radio wave at the channel frequency. Sounds are encoded on this wave as alterations in frequency.
So in rats' brains, the natural frequency of neurons in the cortex can be compared to the frequency of the FM channel, while information about the object a rat is touching is encoded like the sound. Ahissar speculates that rather than simply relaying pulses to the cortex, neurons in the thalamus act as an FM receiver by interpreting the frequency changes, from which rats perceive texture.
• Deutsches Forum •