EBRAINS researchers develop theory on travelling waves of activity in the human brain

Researchers at the Berlin Institute of Health at Charité (BIH) have used brain simulations to develop a theory on the formation of travelling waves of activity. These waves influence cognitive processes in the human brain such as learning or remembering. Understanding travelling waves of activity can support in treating patients with cognitive disorders. The research, powered by the EBRAINS research infrastructure, has been published in Nature Communications.

For the first time, researchers around Professor Dr. Petra Ritter’s team succeeded in explaining the propagation of travelling waves of activity in the human brain using a computer simulation. Previous studies indicate that these waves are important for various cognitive functions such as memory. Professor Dr. Petra Ritter is Johanna Quandt Professor at the Berlin Institute of Health at Charité (BIH) leading the research group for brain simulation. At the same time, she is Head of the Section Brain Simulation at the Department of Neurology and Experimental Neurology at Charité – Universitätsmedizin Berlin. Charité is one of the largest university hospital in Europe and among the founding members of the national node EBRAINS Germany.

A form of brain waves 

Travelling waves of activity are a pattern of neuronal signals that arise when groups of neurons are active at the same time while this synchronous activity travels spatially across the cortex over time. Researchers can visualise the waves using measurements such as electroencephalography (EEG). These waves are caused by a gradual change in frequency across the brain, which in turn is created by differences in how strongly different parts of the brain are connected.

Like waves across the ocean 

Professor Dr. Petra Ritter is convinced that brain waves can be a key to learning processes in the brain, because synchronous activity strengthens the connection: “The wave fronts moving across the brain synchronise the activity of nerve cells, even if they are spatially distant from each other. A well-known theory states that what “fires” together - i.e. is active at the same time - wires together. This means that these waves can provide an important basis for the coordination of plastic changes in the brain, called learning,” explains Petra Ritter. The waves in the brain can travel on various spatial scales and change direction and other skills: “We know that there are various factors influencing the propagation of the waves, but the exact relationships are very complex. With our mathematical models of the brain, it is despite the complexity possible to break down the underlying rules.”  

Travelling waves of activity are important in therapy   

Knowledge of the mechanisms behind the development of travelling waves of activity have the potential to improve the treatment of brain diseases in the future and help to understand these diseases. “For example, in the treatment of schizophrenia, epilepsy or Parkinson's ” adds Petra Ritter. Petra Ritter's team is working towards developing digital brain twins, a type of personalised computational brain model that can be continuously updated with measured data obtained from the patient. This novel approach can also be used to simulate the reaction of a brain to a stimulus. Ritter sees potential in the simulation to plan therapies such as brain stimulation - e.g. deep brain stimulation for Parkinson's disease - but also to plan neurosurgical interventions in a personalised way on the computer and thus make them safer and more efficient: “What previous models have not considered are plastic changes. Understanding the development of wavefronts can now also be used to simulate learning effects in the sense of a change in the brain.” In a next step, the researchers plan to use the model to simulate the long-term effects of external stimulation of the brain, such as transcranial magnetic stimulation (TMS) or deep brain stimulation with inserted electrodes, i.e. when plastic changes occur. In this way, brain research could help doctors in future to use computer simulations to plan which stimulation has the best effect for a sick person.

This simulation was carried out with the support of the following EBRAINS tools: Health Data Cloud, and The Virtual Brain Cloud. The underlying human data can be discovered with the EBRAINS Knowledge Graph.

Publication:
Dominik P .Koller, Michael Schirner, Petra Ritter: “Human connectome topology directs cortical traveling waves and shapes frequency gradients”. Nature Communications volume 15, Article number: 3570 (2024)

Original press release.