Das Elektroenzephalogramm erfasst die elektrische Aktivität des Gehirns auf nicht-invasive Weise mit 256 Elektroden, die auf der Kopfhaut angebracht sind. Dank mathematischer Algorithmen in Kombination mit anatomischer Bildgebung kann man ohne Implantat sehen, was im subkortikalen Teil des Gehirns passiert. © UNIGE
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Again and again, there are some breakthroughs in medicine, some of them groundbreaking, and researchers are gradually discovering more and more of the secrets of life. But one organ of the human body is still largely a mystery to doctors: the brain. In particular, what happens in the deeper areas of our head and how certain areas interact with each other.

It is precisely these subcortical areas of the brain that play a decisive role, especially in motor, emotional and associative activities. Diseases such as Parkinson’s, obsessive-compulsive disorder (OCD) or Tourette’s syndrome are directly related to these areas. Since the subcortical areas of the brain are very difficult to access, treatment of these disorders is also very invasive and difficult.

It is known that two key structures in these areas, the thalamus and the nucleus accumbens, communicate with each other and also with the cortex in order to control superior thinking, i.e. motor, emotional and associative activation, via electrical oscillations. Researchers from the University of Geneva (UNIGE) and the University of Cologne have therefore researched a non-invasive method to use electroencephalography (EEG) together with mathematical algorithms to measure this brain activity externally.

“A dysfunction in this communication causes very severe human diseases such as Tourette and OCD, which usually begin in adolescence with the end of brain development, as well as Parkinson’s disease,” explains Dr. Christoph Michel, Professor at the Institute of Neurosciences at the UNIGE Medical Faculty.

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Treatments based on deep brain stimulation have so far been exclusively invasive. Electrodes had to be implanted in the middle of the brain and electrically stimulated by an external stimulator. “Although this technique has proven to be effective in Parkinson’s disease, it, unfortunately, does not work so well in OCD and Tourette’s syndrome,” says Dr. Martin Seeber of the Department of Basic Neurosciences and first author of the study published in the journal Nature Communications.

Non-invasive analysis techniques

In addition to the traditional treatment methods of measuring and regulating activity in the subcortical area of the brain through implants, doctors sometimes do not even know how they work. In order to successfully treat diseases such as Tourette or OCD, however, it is essential to understand how these subcortical zones function and communicate – if possible without surgery and implants, also in order to increase the number of test subjects.

“We finally see what happens in the deepest part of the brain without having to go directly into it.”

“Of course, we were thinking of the EEG, which records the electrical activity of the brain with 256 electrodes on the scalp,” explains Michel. A team led by Professor Veerle Visser-Vandewalle, a neurosurgeon at the University of Cologne and researchers from the University of Geneva were finally able to carry out a comparative test. They measured the electrical activity of the subcortical regions of four OCD and Tourette patients who had already received electrode implants, while the subjects were also connected to an EEG and the scientists could measure the activity of the same regions from the surface.

“With the mathematical algorithms we developed, we were able to precisely interpret the data provided by the EEG and determine where brain activity comes from,” said Seeber. The result was that both measurements showed the same data. “With signals very similar to those of the implants, we finally proved that the surface EEG enables us to see what happens in the deepest part of the brain without having to go directly into it,” said Professor Michel.

Possibilities for new treatments

“In the hope that we can better understand the causes of diseases such as Tourette and OCD, now that we know that EEG can be used to analyze subcortical zones, we can try to understand how they communicate with each other and with the cortex,” emphasizes Seeber. The scientists also hope to use the technology in the future to improve current treatment methods based on rebalancing network interactions with a very light electric shock. They also want to use them for other diseases such as obesity, addiction or Alzheimer’s. “We hope that, over time, we will be able to stimulate the deep brain areas from the surface with an electromagnetic treatment and thus abolish electrode implants in the brain once and for all,” said Professor Michel.