24.07.2019      13:00

Neurobiology Lecture

 

Rhes engineers intercellular tunnels and transports Huntington disease protein

Srinivasa Subramaniam
Associate Professor
The Scripps Research Institute
Jupiter, Florida, USA

Why selected cell types in the brain die in neurodegenerative disease? For example, in Huntington disease (HD), a genetic disorder, neurons die selectively in the brain’s striatum affecting motor coordination in the patients. Even though the HD mutant gene, mHTT, is present throughout the body and equally distributed, it remains unclear why striatal neurons degenerate in HD.

We discovered that Rhes, a striatal-enriched protein, makes membranous tunneling nanotubes which interact with neighboring cells. Through these membranous tunnels, Rhes can now rapidly transported from cell-to-cell, and also carry mHTT. We propose that such cell-to-cell transport of disease-causing protein in the striatum may lead to dysfunction and death of neurons. Blocking the Rhes-mediated mHTT transport may prevent or delay HD.

 

HS2
Im Neuenheimer Feld 306
Heidelberg

 

31.07.2019      13:00

Neurobiology Lecture

 

Effects of cortico-thalamic feedback on responses in mouse dLGN

Prof. Laura Busse
Department Biology II
LMU Munich

Feed-forward sensory processing is a fundamental model of how the brain mediates visual perception. Using a largely feed-forward architecture, artificial neural networks can now carry out robust and dynamic operations as to rival human perception.

So why then, in the brain is feedback such a prominent and ubiquitous motif? As a model for feedback effects on sensory processing, the cortico-thalamic (CT) circuit has, for over half a century, sparked much interest. Despite these efforts, however, how CT feedback influences the representation of visual information remains poorly understood.

Here, we revisited the fundamental question of cortical feedback’s role in thalamic visual processing. We performed a series of experiments using optogenetic tools for circuit manipulations in awake mice. We found that CT feedback during spontaneous activity enhanced firing rates and reduced bursting, and, during processing of natural movie clips, reduced sparseness of dLGN responses. Hence, CT feedback seems crucial for promoting tonic firing mode in dLGN, potentially allowing a more linear transmission of incoming visual information.

Furthermore, our results indicate that CT feedback shapes spatial processing. Measuring tuning for stimulus size, we found that dLGN RFs in conditions with intact CT feedback were smaller and showed stronger surround suppression. Finally, we demonstrate that these effects on spatial integration might, at least partially, be mediated by neurons in the visual part of TRN, via which CT feedback can exert suppressive effects.

Together, our findings suggest that a function of CT feedback is to enhance responses to local visual signals and shape contextual modulations.

 

HS2
Im Neuenheimer Feld 306
Heidelberg

 
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Human blood cells can be directly reprogrammed into neural stem cells

Foto © M.C. Thier/DKFZ

Scientists from the German Cancer Research Center (DKFZ) and the stem cell institute HI-STEM* in Heidelberg have succeeded for the first time in directly reprogramming human blood cells into a previously unknown type of neural stem cell. These induced stem cells are similar to those that occur during the early embryonic development of the central nervous system. They can be modified and multiplied indefinitely in the culture dish and can represent an important basis for the development of regenerative therapies.

Together with stem cell researcher Frank Edenhofer from the University of Innsbruck and neuroscientist Hannah Monyer from DKFZ and the Heidelberg University Hospital, Andreas Trumpp (German Cancer Research Center (DKFZ) and Director of HI-STEM in Heidelberg) and his team have succeeded in reprogramming different human cells: connective tissue cells of the skin or pancreas as well as peripheral blood cells. "The origin of the cells had no influence on the properties of the stem cells," said Marc Christian Thier, first author of the study. In particular, the possibility of extracting neural stem cells from the blood of patients without invasive intervention is a decisive advantage for future therapeutic approaches. More...


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Open positions at the IZN

  • The Puttagunta group is seeking a highly motivated and qualified M.Sc. student to start a PhD project, the goal of which is to understand the underlying mechanisms that transpire after spinal cord injury that lead toward half of all spinal cord injury patients suffering from neuropathic pain. Methods that will be used: intersectional genetics, cell-specific ablations, use of reporter lines, monosynaptic tracing, tissue clearing and 3D microscope reconstruction, behavioural pain assessments and histology. Adobe
    Posted 07.2019

  • The Acuna group and Katrin Schrenk-Siemens are seeking 2 highly motivated postdoc candidates to work on the recently funded project 'Human pluripotent stem cell-derived neurons as a tool to study central and peripheral nociceptive mechanisms' using RNAseq, electrophysiology, imaging, and super-resolution microscopy. Adobe
    Posted 06.2019

  • The group of Prof. Andreas Draguhn is looking for an outstanding PhD student for a pathophysiological study in cellular neurophysiology to study changes in retinal function following experimental autoimmune optic neuritis, with particular emphasis on alterations in synaptic transmission and glutamate homeostasis. Methods include cellular electrophysiology, microscopy, viral transduction and histological/morphological techniques. Adobe
    Posted 02.2019


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Managing Director:
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IZN-Neurobiology, University of Heidelberg
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D-69120 Heidelberg, Germany

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email:  Bading@nbio.uni-heidelberg.de

 

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IZN-Neurobiology, University of Heidelberg
Im Neuenheimer Feld 366, 1.OG
D-69120 Heidelberg, Germany

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Fax:  +49 - 6221 - 54 16524
email:  Braeunling@nbio.uni-heidelberg.de

 

Administration & Information:
Irmela Meng
IZN-Neurobiology, University of Heidelberg
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D-69120 Heidelberg, Germany

Phone:  +49 - 6221 - 54 16501
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Latest Revision: 2019-07-16
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