Summary: Study reveals how rhythmic brain activity shapes our perception.
Source: DPZ
Contrary
to our intuition, the precision with which we perceive the real world
is not stable in time, rather it rhythmically fluctuates between high
precision and low precision states several times per second. These
fluctuations follow rhythmic electrical activities in the brain.
Electrical rhythms of the brain range across different frequencies, from
1 to 250 hertz.
Using
these different frequencies the brain regulates how relevant
information is transmitted between different brain regions. A group of
neuroscientists from the German Primate Centre, Goettingen, Germany and
the University of Melbourne, Australia has critically reviewed the
evidence on this subject and shows how these frequencies may determine
fundamental perceptual processes in the brain.
Cross-frequency coupling enables selective attention
One
basic phenomenon observed throughout brain areas is that slower rhythms
(approx. 4 to 8 hertz) modulate the strength of a faster rhythm
(approx. 40 to 80 hertz). This is known as cross-frequency coupling. The
pair of frequencies coupled to each other varies, based upon the
cortical area and its function for behavior.
In
some instances, attention may cause nerve cells to become
de-synchronized, allowing them to carry different informations, like
when one string instrument plays a different melody from the rest of the
orchestra. In others, attention may lead to the activation of large
numbers of neurons to maximize their impact.
“These
two different functions may be organized in the brain through cross
frequency coupling,” says Moein Esghaei, one of the authors.
Distinguishing between different types of information
The
simultaneous existence of different frequency bands in the brain also
helps tagging different modalities of information arriving at the same
brain region. For example colour and direction of a hang glider flying
in the sky.