Mathematical modelling brings brain insights

Can we see what is happening in the brain? Yes, we can in a sense, using imaging technology. But the processes in the brain remain to a large extent mysterious. Researchers are now using modelling to help understand these processes.

Maria Engström next to a magnetic resonance scanner.Maria Engström at the magnetic resonance camera at CMIV. Photo credit Kajsa JuslinWhen you memorise a telephone number, read a book, or answer a question different parts of your brain become active. The blood flow increases in the activated regions. Such brain activity can be investigated with a magnetic resonance scanner, or – to be more accurate – functional magnetic resonance imaging, “fMRI”. It has long been known that the measured signal depends on the supply of oxygen in the blood, but the exact significance of the signal is still not clear.Maria Engström at the magnetic resonance camera at CMIV.Maria Engström at the magnetic resonance camera at CMIV. Photo credit Kajsa Juslin

“How is the supply of oxygen in the blood linked to what happens in the nerve cells? The signal varies with time, of course, so we believe that it reflects a dynamic biological process”, says Maria Engström, professor of medical imaging in the Department of Health, Medicine and Caring Sciences (HMV) at LiU.

Originally a theoretical physicist, she is very interested in processes. Her work as a doctoral student involved quantum modelling of molecules. She has taken her knowledge of how models can help understand and predict processes into the world of medicine. When she saw brain imaging for the first time, her curiosity was immediately aroused: is it possible to construct mathematical models of the biological processes in the brain? Other scientists said it was impossible. So she decided to wait, but never gave up the idea of taking a step forwards in understanding what is actually measured by fMRI.

Maria Engström’s research group collaborates with other groups, one of them Gunnar Cedersund’s group in integrative systems biology, in the mathematical modelling of brain function. The starting point of the work is theories from other researchers about what is happening. The next step then is to construct the models, which consist of equations that describe each step in such a theory, from the activation of a nerve cell to how the blood flow changes.

“The clever part of the modelling is that we can determine whether it is possible to achieve the results predicted by the theory. If the model cannot describe real data in a realistic way, we can conclude that the theory being tested is unfounded.”

Many questions left to answer

The researchers are currently studying how the healthy brain functions. The models can also be used to simulate and predict various processes. Maria Engström hopes that such knowledge may, in the long term, be useful in understanding the mechanisms of various diseases.Maria Engström showing an image of a brain on her computer screen.Maria Engström is particularly interested in the link between what we can measure, such as electrical activity in nerves and the concentrations of hormones, and our subjective experience. Photo credit Kajsa Juslin

“We hope in the future that we can use the models to understand what happens when the brain is not functioning properly. We want to understand which factors we must change to treat the disease, and to use our models to simulate different treatment alternatives.”

There are many questions in brain research that we cannot answer. Maria Engström is particularly interested in the link between what we can measure, such as electrical activity in nerves and the concentrations of hormones, and our subjective experience.

“We can understand the brain to a certain extent at a purely biological level, but we experience things as people, and our thoughts control a great deal of our lives. It would be interesting to know how our thoughts are linked to physiology and our general wellbeing.”

Translated by George Farrants

The article has also been published (in Swedish) in Forskning & Utveckling, no. 1/2020.

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