Research in synch
Romanian partner group of the Max Planck Institute for Brain Research in Frankfurt studies rhythmic activity of nerve cells in the brain
For the human brain, even simple objects are very complex: for example, a child's building block has a certain colour, shape and surface finish. In order that the brain recognise all of these characteristics as belonging together, nerve cells in different brain regions need to become jointly active. This kind of synchronisation of nerve cell activity is what the partner group of the Max Planck Institute for Brain Research in Frankfurt is working on. The group, led by Raul Muresan from the Centre for Cognitive and Neural Studies in Cluj-Napoca, Romania, is keen to find out how networks of nerve cells synchronise their activity and form patterns known as oscillations. Since 2008 they have been working on the subject closely with Wolf Singer and his fellow scientists from the Frankfurt-based Max Planck Institute.
Raul Muresan, a former colleague of Singer's in Frankfurt, has worked at the Institute in Cluj-Napoca since 2007: "This cooperation with the Max Planck Institute for Brain Research represents an immense enrichment for our scientific work. My colleagues and I regularly spend lengthy periods in Frankfurt, where we share our experience and findings." A cooperation which is also beneficial to the scientists in Frankfurt: "Cluj-Napoca is an important centre for informatics in Eastern Europe. There’s a lot of very valuable expertise that we can use to do things like develop computer simulations of neural networks in the brain. At the same time, we want to strengthen the research landscape in Romania," says Wolf Singer.
One aspect Muresan's team is interested in is the way in which cells coordinate their activity with one another. For instance, nerve cell networks in the visual cortex of the brain are active at frequencies of between 20 and 80 Hertz. These oscillations are formed by the complex interplay of excitatory and inhibitory cells. The electrical properties of the cell membrane play an important role in this. They determine whether a cell processes all electrical stimuli or whether it prefers stimuli of a certain frequency. The scientists study this using microelectrodes to measure the activity of many nerve cells simultaneously. They also employ computer simulations to analyse the extensive nerve cell networks in the brain.
Furthermore, the scientists in Romania, in conjunction with their colleagues in Frankfurt, measure brain waves in the human brain. The electroencephalograms (EEG) enable them to see whether the synchronised and oscillatory activity of the nerve cells is involved in the conscious perception of objects. To do this, they have developed special experiments that involve showing volunteers objects on a screen and changing their perception. They then measure the point from which the study participants can perceive the object as such. The scientists also record the change in brain activity which occurs when an object suddenly becomes perceivable.