Document Actions

You are here: Home / Research / Meet the Scientist / Michael Brecht

Michael Brecht

Bernstein Center Berlin,
Humboldt-Universität Berlin

brecht150

In 2006, Michael Brecht took up the appointment as professor for 'Systems Neurobiology and Neural Computation' at the Bernstein Center for Computational Neuroscience Berlin. The professorship is financed for the first 5 years by the German Federal Ministry of Education and Research and is then continued by the Humboldt-Universität zu Berlin.

Single cells in the context of the brain

Thanks to tissue and cell culture experiments, we have a good understanding of how single neurons work. However, due to the enormous complexity of the brain, it has so far been extremely diffi cult to investigate the contribution of single cells to its overall function. Although it has long been possible to eavesdrop on neuronal activity with extracellular methods, in the intact brain there is no way to manipulate single cells or use intracellular methods to precisely describe their activity. “As yet, the analysis of cellular processes and the analysis of cellular activity in the living brain are worlds apart,” says Michael Brecht. Bridging the gap between these worlds is a central theme of his work. “We want to understand the function of single cells in the systemic context of the brain,” says Brecht. What is the role of a single cell, embedded into this complex network? What effect can it have? Brecht, currently at the Erasmus University Rotterdam, has accepted the professorship “Animal Physiology /Systems Neurobiology and Neural Computation” at the Bernstein Center for Computational Neuroscience in Berlin. He will join the Institute for Biology at the Humboldt University Berlin in fall 2006.

Brecht has been interested in the neuronal basis of behavior since researching his diploma thesis at the University of California. In his doctoral thesis in the lab of Wolf Singer at the Max Planck Institute for Brain Research in Frankfurt, Brecht investigated temporal coding in the midbrain of cats. From 1999 to 2004, he led an independent research group in the department of Bert Sakmann at the Max Planck Institute for Medical Research in Heidelberg. After completing his habilitation thesis in 2004, he moved to the Neuroscience Department of the Medical Center in the Erasmus University Rotterdam as an assistant professor.

In his diploma thesis, Brecht addressed questions concerning the tactile perception of the rat and returned to this field after his doctoral studies – because of the “elegance of the system,” as he says. In the regions of the cortex where tactile stimuli are processed and the movement of vibrissae is controlled, each vibrissa is represented through an easily identifi able group of cells. This makes tactile perception a very good system to investigate structure-function relationships. In addition, tactile movements of the rat vibrissae are very simple compared to the coordination of arm or fi nger movements. Vibrissae can only be moved forwards or backwards and these movements can be quantifi ed very precisely. “Through a combination of cellular data and measurements in the intact brain, we are gradually approaching a quantitative description of the whole network, which cannot be said for other brain regions,” says Brecht.

In experiments on living animals, Brecht investigated the contribution of a single cell to the movement program of the vibrissae. “It used to be an implicit assumption that the activity of very large groups of cell is required to trigger any movement,” explains Brecht. However, the results of a number experiments strongly suggested to Brecht and his colleagues that the cells in the motor cortex, which control movement, exhibit far less activity than previously believed. This observation led them to suspect that the activity of single cells could be far more meaningful than assumed. They stimulated single cells in the motor cortex and found that it did indeed induce a movement program – the rats moved their vibrissae. “There are over a million cells in the vibrissae motor cortex – it is quite astonishing that the animal reacts with a clearly visible and complex movement to slight activity in just one cell,” says Brecht.

In order to target individual cells in the brain more precisely than previously possible, Brecht uses modern microscopy technologies and has contributed to their improvement. Classical neurophysiological experiments in living animals are “blind”–the scientists stimulate cells or measure their activity without knowing which cell type they are looking at. The cells can only be identified in retrospect, if at all, by marking them and subsequently analyzing them in slice. This procedure is tedious; furthermore, investigations of rare or very small cells are not possible. With the help of two-photon microscopy, fluorescently labeled cells can be identified in situ in the brain of the living animal. Brecht has combined this technology with neurophysiological methods and developed the method of „two-photon targeted patching“ (TPTP). Through TPTP, it is possible to target fluorescently labeled cells in the living brain and measure their activity. “Such experiments have been carried out in tissue slices on cells identified under the microscope for about a decade. The ability to specifically record the activity of defined cells revolutionized the field of cellular brain physiology. It opened the door for an entirely different type of experiment,” explains Brecht. “We hope that TPTP has a similar potential and will enable new experimental approaches for investigations of the intact brain.”

 

Contact





Prof. Dr. Michael Brecht
Bernstein Center Berlin

Humboldt-Universität zu Berlin

Philippstr. 13, Haus 6

10115 Berlin
Tel: +49 (0)30 2093 6718
Email: michael.brecht@bccn-berlin.de

Website of Michael Brecht