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Ilka Diester

Bernstein Awardee 2012
Ernst Strüngmann Institute for Neuroscience in Cooperation with Max Planck Society

“And now we deactivate this brain area here for a short period of time,” says Ilka Diester, “and watch how the neighboring area will respond to its failure,” as she keenly studies the monitor displaying the neuronal impulses recorded from the second brain region. In her research, Ilka Diester deals with the question of how the motor cortex encodes movements. She is particularly interested in sensorimotor circuits: What information does the motor cortex receive? To which other brain areas does it itself send signals? And what happens if these motor circuits are disrupted—are there stabilization mechanisms by which the brain can cope with small damages? Using theoretical models and experiments, Ilka Diester will pursue these questions in a project supported by the Bernstein Award. Since July 2013, she has been a laureate of the 2012 Bernstein Award.

Porträt Ilka Diester

Ilka Diester

In her research approach, Diester combines two important experimental tools of neuroscience: optogenetics and electrophysiology. By optogenetic interventions, she induces specific perturbations in a local area of the motor cortex to temporarily activate or deactivate it. At the same time, she records the nerve cell activity in a remote motor area and observes the impact of the silencing or the overactivation of the first brain region on the second. How does area 2 react when area 1 is modulated—does it immediately try to counteract to compensate for the change of neuronal activity? “The results will allow us to deduce which robust mechanisms the motor cortex has to counterbalance small damages in the short term,” Diester says.

Born in Finland and raised in small towns in Sweden and in Northern Germany, Ilka Diester moved to Berlin to study biology. As a young student, she attended the math lectures of Andreas Herz (nowadays speaker of the Bernstein Project Committee and coordinator of the Bernstein Center Munich)—who inspired her enthusiasm for neuroscience. Apart from that, Diester develop-ed two additional main scientific interests over the course of her undergraduate studies: genetics and computer science. Already early on, she realized that she wanted to work on a medically relevant topic. After her thesis on a genetic disease, she completed a PhD in the group of Andreas Nieder at the Hertie Institute for Clinical Brain Research in Tübingen. In her doctoral thesis, she investigated how neurons in the prefrontal and parietal cortex encode cognitive categories—such as numerical values—using in vivo electrophysiology. At that time, she realized the importance of basic research for medical progress. “Only when we understand the working principles of the brain, will we be able to detect faulty processes and develop new therapies,” says Diester.

In 2008, Ilka Diester moved to Stanford University in the United States. There, she had the opportunity to do a combined postdoc in two scientific groups, and hence to integrate her two scientific backgrounds in genetics and neuroscience. In the lab of Karl Deisseroth, she first came into contact with optogenetics. This method merges genetic and optical techniques to stimulate specific types of nerve cells or circuits with light. For this purpose, light-sensitive membrane proteins are built in the cell membranes of neurons by means of genetic vectors. As a consequence, the nerve cells become light sensitive: whenever they come in contact with light of a specific wavelength, they change their firing behavior. Depending on the type of the inserted membrane protein, the neuron is activated or deactivated for the duration of stimulation and can thus be literally “turned on or off”. In the Deisseroth lab, Ilka Diester also learned how to combine optogenetics with behavior and electrophysiology to investigate specific neuronal circuits.

Meanwhile, in the group of Krishna Shenoy, she dealt with the development of neuroprosthetics and deepened her knowledge of dynamic systems theory, as applied to the motor system. Diester found her stay at Stanford extremely motivating: “The local motto seems to be ‘the sky is the limit’—as long as you bring the right skills and capabilities, only you yourself are your limiting factor. With a strong will and working hard, you can achieve anything you want there.” During this period, Ilka Diester managed to establish optogenetic techniques in the motor system of non-human primates for the first time. At that time, this method had only previously been applied in rodents.

Ilka Diester_Labor

Ilka Diester working in her lab

With a clearly defined research field of her own—the combination of optogenetics and neuroprosthetics—the neurobiologist returned to Germany in 2011. At the Ernst Strüngmann Institute in Cooperation with the Max Planck Society in Frankfurt, Diester built up her junior research group. Together with her lab members, she examines the fundamentals of sensorimotor circuits in rodents and rhesus monkeys. As described above, on the one hand she is interested in which robust mechanisms the motor cortex has to react to minor failures that may occur, for example, as a result of a stroke. On the other hand, Diester examines similarities and differences of optogenetic and electrical stimulation: The motor cortex seems to respond much more sensitively to electrical than to light stimulation. For her work, she received the Boehringer Ingelheim FENS Award last year, and this year, a Starting Grant by the European Research Council.

By means of the Bernstein Award grant, Ilka Diester will now further deepen the theoretical aspects of her work and will in-creasingly make use of computer models. Hereby, she hopes to be able to analyze her experimental data even more thoroughly—and to find out in detail how neural networks readjust if a certain component is silenced or overactivated. The long-term goal of Diester’s research is to gain a solid understanding of the motor cortex circuits, which is a prerequisite for developing neural prostheses. For example, it is conceivable that one could develop an electrically controlled prosthesis with which the pa-tient receives feedback on tactile information. Until now, human subjects must solely rely on visual information when lifting a glass by a controlled robot arm. A built-in sensor in the fingertip of the prosthesis could inform the brain via optogenetic techniques that the hand needs to grasp firmer to prevent the water glass from slipping. “This would be an example of how optoge-netics could be applied in daily life,” Diester says. “However, these prospects still lie in the far future. We are working on the way to get there,” she says and takes a critical look at the mo-nitor, showing the nerve cell responses.