Focusing on what is important – this is one of the main tasks of our brain. After all, countless amounts of information are constantly flooding our senses. But how do you separate the important from the insignificant? It has long been known that oscillatory neuronal activity is a key factor in this attentional selection in the mammalian brain. Scientists from the German Primate Center in Göttingen and the University of Melbourne have now studied how it works. They found that coupling lower frequencies of oscillations with higher frequencies helps fine-tune the brain and thus forms the basis for higher cognitive functions, such as selective attention (Trends in Neuroscience).
Contrary to our intuition, the precision with which we perceive the real world is not stable over time, but rhythmically oscillates between high-precision and low-precision states several times per second. These fluctuations follow the rhythmic electrical activities in the brain. The electrical rhythms of the brain span different frequencies, from 1 to 250 hertz. Using these different frequencies, the brain regulates how relevant information is transmitted between different regions of the brain. A group of neuroscientists from the German Primate Center in Goettingen, Germany, and the University of Melbourne, Australia, have critically reviewed the evidence on this and show how these frequencies can determine fundamental perceptual processes in the brain. .
Interfrequency coupling enables selective attention
A basic phenomenon observed in all areas of the brain is that slower rhythms (about 4-8 hertz) modulate the strength of a faster rhythm (about 40-80 hertz). This is called interfrequency coupling. The pair of frequencies coupled to each other varies depending on the cortical area and its behavior function. In some cases, attention can cause nerve cells to get out of sync, allowing them to carry different information, such as when a string instrument plays a different melody than the rest of the orchestra. In others, attention can lead to the activation of a large number of neurons to maximize their impact. “These two different functions can be organized in the brain by cross-frequency coupling,” explains Moein Esghaei, one of the authors.
Distinguish between different types of information
The simultaneous existence of different frequency bands in the brain also makes it possible to mark different modalities of information arriving at the same region of the brain. For example the color and direction of a hang glider flying in the sky. “Our brain carries color and motion information through different frequencies to higher-order brain areas, much like telecommunication systems carry different types of information to the same receiver,” says Moein Esghaei.
Understanding Neurological Diseases
“The rhythmic activity of neural networks plays an essential role for visual perception in humans and other primates”, summarizes Stefan Treue, head of the laboratory for cognitive neuroscience at the German Primate Center as co-author. “Understanding exactly how these patterns of activity interact and are controlled not only helps us better understand the neural basis of perception, but can also help elucidate some of the perceptual deficits in neurological conditions, such as dyslexia, ADHD and schizophrenia.”
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Material provided by Deutsches Primatenzentrum (DPZ)/German Primate Center. Note: Content may be edited for style and length.