27. Sept. 2023
For the more than six million people in the world suffering from this neurodegenerative disease, symptomatic treatment offers great relief. After dopaminergic therapy, deep brain stimulation (DBS), which uses electrical impulses to influence the brain functions altered by the disease, also contributes to a significant improvement in patients' lives. It works by inserting an electrode into a target area deep in the brain, which is connected to a stimulator located under the skin in the subclavicular region and stimulates a region in the brain (most often the subthalamic nucleus) with electrical impulses. These impulses affect the communication between those parts of the brain that are related to the symptoms of the disease and bring it closer to the state of a 'healthy brain'.
This therapy has been very successful, but scientists still have not figured out exactly how the brain stimulation mechanism works, what possible side effects it may have and how it may affect the overall functioning of the brain. That is why they are proceeding step by step in their search. One of the pieces of the puzzle is the work of the Brno scientists, published in the prestigious journal Nature Parkinson’s disease.
In this study, the researchers monitored changes in the electrical activity of the brain of patients with Parkinson's disease when brain stimulation with DBS was switched on and off and compared them with healthy controls. Using the non-invasive measurement method HD-EEG (high-density electroencephalography) in the Multi-modal and Functional Neuroimaging Laboratory of CEITEC MU and subsequent analysis of brain electrical activity, the researchers described differences in the dynamics of EEG microstates, which reflect the behaviour of so-called large-scale brain networks. These include a large number of functionally connected brain regions and their involvement appears to be crucial for successful cognitive functioning. Research showed that some of the identified microstates were affected by non-motor symptoms of the disease on which DBS had no effect, but one microstate was specific to motor symptoms and was modulated by stimulation.
"Together with neurologist Martina Bočková, who has a long-standing interest in electrophysiology in Parkinson's disease, we decided to use a similar approach to assess the dynamics of brain networks in the context of the DBS effect as I used in my previous work on the search for biomarkers of the prodromal stage of dementia. The aim was to provide a different perspective on the electrophysiology of Parkinson's disease symptoms and the effect of DBS on brain network function, to lay the foundations for the search for clinically applicable biomarkers of DBS therapy and, last but not least, to contribute to the physiological interpretation of the identified microstates," says the publication's lead author, Martin Lamoš.
The field of research, which was started years ago and is led by renowned neuroscientist Ivan Rektor from the Centre for Brain and Mind Research at CEITEC MU, is specific in its multidisciplinary approach. In addition to biomedical engineer Martin Lamoš, the research also involved psychologist Sabina Goldemundová, neurosurgeon Jan Chrastina, neurologist Martina Bočková and nurse Veronika Pulkrábková and other experts from the neuroscience programme at CEITEC MU and St. Anne's University Hospital in Brno. However, the patients who decide to participate in the research activities excel in the lead role. Approximately twenty of them undergo deep brain stimulation in Brno every year.
Parkinson's disease is characterised by varying degrees of motor and a range of non-motor symptoms, and patients' responses to different types of therapy are individual. It is the analysis of the microstates that could play a role in adjusting the individual therapy to patients with this neurodegenerative disease.
"When a patients’ tremor disappears by switching on stimulation, they perceive it as a miracle. Our job is then to find out how it all works – the best job in the world for an engineer," concludes Martin Lamoš.