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Hermann Cuntz

Bernstein Awardee 2012
Bernstein Focus: Neurotechnology in Frankfurt,
Frankfurt Institute for Advanced Studies,
Ernst Strüngmann Institute for Neuroscience in Cooperation with Max Planck Society

Numerous delicate branches emerge from a small thickening and extend out to all directions. One of them runs vertically upwards, ramifying into the finest structures. When an ordinary person looks at Hermann Cuntz’ images for the first time, he sees widely branched treetops, trunks and roots—similar to a dense forest. A neuroscientist, in turn, recognizes the pictures as microscopy images of neurons. However, both are wrong: Cuntz‘ display artificially created neurons. Using theoretical models and equations, the biologist generates the neuronal trees using the computer. The long-term goal of Cuntz’ research is gaining a basic understanding of the principles of neuronal morphology. In September, Hermann Cuntz received the Bernstein Award 2013 for his work.

Cuntz_Porträt

Hermann Cuntz

“I am interested in the effects of shape and morphology of nerve cells on the structure and function of neuronal circuits,” Hermann Cuntz explains. According to which principles do nerve cells form small networks in the brain? Is there a basic connection code?“ Hermann Cuntz came in contact with theoretical neuroscience during his diploma thesis under the supervision of Alexander Borst at the Friedrich Miescher Laboratory of the Max Planck Society in Tübingen. Borst sparked the young biologist‘s enthusiasm for brain research—and employed him as a doctoral student in his research group. During his PhD, Cuntz examined the visual system of the fly, also conducting experimental studies. However, for him, the successful modeling of a visual circuit in the fly brain turned out to be more important than intracellular recordings. “Having a theoretical model at the end of the day, that can make accurate predictions about reality, is a great feeling”, the neuroscientist says.

Cuntz, who is half German, half French, followed Borst to the University of California at Berkeley (USA), and later to the Max Planck Institute of Neurobiology in Munich during his PhD. In Munich, he received his doctorate in 2004. He then spent two years as a postdoctoral fellow in Igan Segev‘s laboratory at the Hebrew University in Jerusalem. By means of a Minerva scholarship, Cuntz investigated the morphology of dendrites in Israel. For this, he planned to use the minimum spanning tree algorithm—a method that is often applied to connect points distributed in space with minimum distances. The project had barely begun when he wanted to clear his mind from other projects and started to study the algorithm during a lunch break. He soon realized that it often produced spiral structures, resulting in relatively long path lengths. “These were unrealistically long for dendrites that must transmit the neuronal signals as quickly as possible,” the biologist concluded. Cuntz changed this feature of the algorithm and added a constraint to produce short paths in the resulting dendritic tree. He thereby developed a new method that he would later name “morpho-logical modeling” and that constitutes the basis for his ongoing work.

Using morphological modeling, Cuntz can create nerve cells of diverse shapes—or morphology—on the computer. Next to using the shortest feasible path, more parameters are included in the underlying formula, such as the number of contact points with neighboring neurons or the properties of the space that the dendritic tree innervates. “Interestingly, some of these criteria have already been postulated by the Spanish anatomist Ramón y Cajal in the early 19th Century,” Cuntz says. “Nowa-days, I use it to form anatomically realistic models of neurons and neuronal networks.” His synthetic neurons are so lifelike that even experienced neuroanatomists cannot distinguish the artificially generated cells from natural ones. During another Postdoc stay in Michael Häusser‘s lab at University College London, Hermann Cuntz extended his model to other types of nerve cells. This way, he may now create synthetic granule, pyramidal, and Purkinje cells next to neurons of the fly. “When I first presented the images of these cells in the lab, even experienced neurophysiologists could not identify them within a set of real neurons—they practically passed the classical Turing test,” Cuntz says. The realism of his neurons has also been validated statistically. By now, the computer software developed by Cuntz is used by scientists all over the world to replicate the brain’s structure in large-scale projects, such as the Human Brain Project.

Cuntz_synthetische Neurone

Synthetically generated pyramidel cells by Hermann Cuntz. With this picture, Cuntz won the Wellcome Image Award 2011.

Since 2011, Hermann Cuntz is at the Ernst Strüngmann Institute (ESI) for Neuroscience in collaboration with the Max Planck Society in Frankfurt. His lab will be located there as well as at the Frankfurt Institute for Advanced Studies (FIAS) where he will extend the Bernstein Focus: Neurotechnology. By means of the Bernstein Award, the new father of twin girls plans to examine how nerve cells perfectly combine to small networks based on their shape. In a second approach, he will look at the impact of the circuit’s conformation on its own activity and dynamics. In this way, he wants to decipher the relationship between structure and function of neural connections. “For me, neuronal morphology, meaning the shape of nerve cells, is the starting point to derive general rules about neural connections and functions,” the neuroscientist explains.

In order to pursue the questions about wiring principles in the brain, Hermann Cuntz plans to further deepen his collaborations with experimental and theoretical neuroscientists. This way, he can assess the realism of his network models and their predictions and may constantly develop them further. Next to research, music takes an important role in the life of the scientist. In his spare time he likes to play music with his wife at the piano. At conferences and summer schools, Cuntz has given small concerts together with other scientists. During these occasions, Eli Nelken, a neurobiologist from Jerusalem, typically accompanies him on the piano while Cuntz takes over the singer’s part. “Music is an ideal opportunity to meet people. With some fellow neuroscientists I first made contact during these music sessions,” Cuntz reports. Next August, he will organize together with Jochen Triesch a summer school on Computational Neuroscience in Frankfurt. He is looking forward to sharing science and music with all attending neuroscientists.