Max Planck Institute for Experimental Medicine
Gottingen, Germany

The Max Planck Institute of Experimental Medicine is located in Göttingen, Germany. It was founded as Kaiser Wilhelm Institute for Medical Research in 1947, and was renamed in 1965. It is one of 80 institutes in the Max Planck Society . Prof. Dr. Klaus-Armin Nave is currently the acting director of the institute. Wikipedia.

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Gutig R.,Max Planck Institute for Experimental Medicine
Science | Year: 2016

The brain routinely discovers sensory clues that predict opportunities or dangers. However, it is unclear how neural learning processes can bridge the typically long delays between sensory clues and behavioral outcomes. Here, I introduce a learning concept, aggregatelabel learning, that enables biologically plausible model neurons to solve this temporal credit assignment problem. Aggregate-label learning matches a neuron's number of output spikes to a feedback signal that is proportional to the number of clues but carries no information about their timing. Aggregate-label learning outperforms stochastic reinforcement learning at identifying predictive clues and is able to solve unsegmented speech-recognition tasks. Furthermore, it allows unsupervised neural networks to discover reoccurring constellations of sensory features even when they are widely dispersed across space and time.

Nave K.-A.,Max Planck Institute for Experimental Medicine | Werner H.B.,Max Planck Institute for Experimental Medicine
Annual review of cell and developmental biology | Year: 2014

Myelination of axons in the nervous system of vertebrates enables fast, saltatory impulse propagation, one of the best-understood concepts in neurophysiology. However, it took a long while to recognize the mechanistic complexity both of myelination by oligodendrocytes and Schwann cells and of their cellular interactions. In this review, we highlight recent advances in our understanding of myelin biogenesis, its lifelong plasticity, and the reciprocal interactions of myelinating glia with the axons they ensheath. In the central nervous system, myelination is also stimulated by axonal activity and astrocytes, whereas myelin clearance involves microglia/macrophages. Once myelinated, the long-term integrity of axons depends on glial supply of metabolites and neurotrophic factors. The relevance of this axoglial symbiosis is illustrated in normal brain aging and human myelin diseases, which can be studied in corresponding mouse models. Thus, myelinating cells serve a key role in preserving the connectivity and functions of a healthy nervous system.

Gutig R.,Max Planck Institute for Experimental Medicine
Current Opinion in Neurobiology | Year: 2014

Recent experimental reports have suggested that cortical networks can operate in regimes were sensory information is encoded by relatively small populations of spikes and their precise relative timing. Combined with the discovery of spike timing dependent plasticity, these findings have sparked growing interest in the capabilities of neurons to encode and decode spike timing based neural representations. To address these questions, a novel family of methodologically diverse supervised learning algorithms for spiking neuron models has been developed. These models have demonstrated the high capacity of simple neural architectures to operate also beyond the regime of the well established independent rate codes and to utilize theoretical advantages of spike timing as an additional coding dimension. © 2014.

Burgalossi A.,Max Planck Institute for Experimental Medicine
Nature protocols | Year: 2012

Neurotransmitter release is triggered by membrane depolarization, Ca(2+) influx and Ca(2+) sensing by the release machinery, causing synaptic vesicle (SV) fusion with the plasma membrane. Interlinked is a complex membrane cycle in which vesicles are tethered to the release site, primed, fused and recycled. As many of these processes are Ca(2+) dependent and simultaneously occurring, it is difficult to dissect them experimentally. This problem can be partially circumvented by controlling synaptic Ca(2+) concentrations via UV photolysis of caged Ca(2+). We developed a culture protocol for Ca(2+) uncaging in small synapses on the basis of the generation of small glia cell islands with single neurons on top, which are sufficiently small to be covered with a UV-light flash. Neurons are loaded with the photolabile Ca(2+)-chelator nitrophenyl-EGTA and Ca(2+) indicators, and a UV flash is used to trigger Ca(2+)-uncaging and SV fusion. The protocol takes three weeks to complete and provides unprecedented insights into the mechanisms of transmitter release.

Bakhti M.,Max Planck Institute for Experimental Medicine
Cellular and molecular life sciences : CMLS | Year: 2014

Rapid nerve conduction requires the coating of axons by a tightly packed multilayered myelin membrane. In the central nervous system, myelin is formed from cellular processes that extend from oligodendrocytes and wrap in a spiral fashion around an axon, resulting in the close apposition of adjacent myelin membrane bilayers. In this review, we discuss the physical principles underlying the zippering of the plasma membrane of oligodendrocytes at the cytoplasmic and extracellular leaflet. We propose that the interaction of the myelin basic protein with the cytoplasmic leaflet of the myelin bilayer triggers its polymerization into a fibrous network that drives membrane zippering and protein extrusion. In contrast, the adhesion of the extracellular surfaces of myelin requires the down-regulation of repulsive components of the glycocalyx, in order to uncover weak and unspecific attractive forces that bring the extracellular surfaces into close contact. Unveiling the mechanisms of myelin membrane assembly at the cytoplasmic and extracelluar sites may help to understand how the myelin bilayers are disrupted and destabilized in the different demyelinating diseases.

Simons M.,Max Planck Institute for Experimental Medicine | Simons M.,University of Gottingen | Lyons D.A.,University of Edinburgh
Current Opinion in Cell Biology | Year: 2013

The formation of myelin in the central nervous system is a multi-step process that involves coordinated cell-cell interactions and dramatic changes in plasma membrane architecture. First, oligodendrocytes send our numerous highly ramified processes to sample the axonal environment and decide which axon(s) to select for myelination. After this decision is made and individual axon to oligodendrocyte contact has been established, the exploratory process of the oligodendrocyte is converted into a flat sheath that spreads and winds along and around its associated axon to generate a multilayered membrane stack. By compaction of the opposing extracellular layers of membrane and extrusion of almost all cytoplasm from the intracellular domain of the sheath, the characteristic membrane-rich multi-lamellar structure of myelin is formed. Here we highlight recent advances in identifying biophysical and signalling based mechanisms that are involved in axonal selection and myelin sheath generation by oligodendrocytes. A thorough understanding of the mechanisms underlying these events is a prerequisite for the design of novel myelin repair strategies in demyelinating and dysmyelinating diseases. © 2013 Elsevier Ltd.

Pardo L.A.,Max Planck Institute for Experimental Medicine | Stuhmer W.,Max Planck Institute for Experimental Medicine
Nature Reviews Cancer | Year: 2014

Potassium channels are transmembrane proteins that selectively facilitate the flow of potassium ions down an electrochemical gradient. These molecules have been studied in great detail in the context of cell excitability, but their roles in less cell type-specific functions, such as cell proliferation, angiogenesis or cell migration, have only recently been assessed. Moreover, the importance of these channels for tumour biology has become evident. This, coupled with the fact that they are accessible proteins and that their pharmacology is well characterized, has increased the interest in investigating potassium channels as therapeutic targets in cancer patients.

Nave K.-A.,Max Planck Institute for Experimental Medicine
Nature | Year: 2010

The myelination of axons by glial cells was the last major step in the evolution of cells in the vertebrate nervous system, and white-matter tracts are key to the architecture of the mammalian brain. Cell biology and mouse genetics have provided insight into axon-glia signalling and the molecular architecture of the myelin sheath. Glial cells that myelinate axons were found to have a dual role by also supporting the long-term integrity of those axons. This function may be independent of myelin itself. Myelin abnormalities cause a number of neurological diseases, and may also contribute to complex neuropsychiatric disorders. © 2010 Macmillan Publishers Limited. All rights reserved.

Castillo-Gomez E.,Max Planck Institute for Experimental Medicine
Molecular Psychiatry | Year: 2016

Autoantibodies of the IgG class against N-methyl-d-aspartate-receptor subunit NR1 (NMDAR1) were first described in anti-NMDAR encephalitis and seen as disease indicators. Recent work on together over 5000 individuals challenged this exclusive view by showing age-dependently up to >20% NMDAR1-autoantibody seroprevalence with comparable immunoglobulin class and titer distribution across health and disease. The key question therefore is to understand the properties of these autoantibodies, also in healthy carriers, in order to assess secondary complications and possible contributions to neuropsychiatric disease. Here, we believe we provide for human NMDAR1-autoantibodies the first comprehensive analysis of their target epitopes and functionality. We selected sera of representative carriers, healthy or diagnosed with very diverse conditions, that is, schizophrenia, age-related disorders like hypertension and diabetes, or anti-NMDAR encephalitis. We show that all positive sera investigated, regardless of source (ill or healthy donor) and immunoglobulin class, provoked NMDAR1 internalization in human-induced pluripotent stem cell-derived neurons and reduction of glutamate-evoked currents in NR1-1b/NR2A-expressing Xenopus oocytes. They displayed frequently polyclonal/polyspecific epitope recognition in the extracellular or intracellular NMDAR1 domains and some additionally in NR2A. We conclude that all circulating NMDAR1-autoantibodies have pathogenic potential regarding the whole spectrum of neuronal NMDAR-mediated effects upon access to the brain in situations of increased blood–brain–barrier permeability.Molecular Psychiatry advance online publication, 9 August 2016; doi:10.1038/mp.2016.125. © 2016 The Author(s)

Kassmann C.M.,Max Planck Institute for Experimental Medicine
Biochimie | Year: 2014

Peroxisomes are cellular compartments primarily associated with lipid metabolism. Most cell types, including nervous system cells, harbor several hundred of these organelles. The importance of peroxisomes for central nervous system white matter is evidenced by a variety of human peroxisomal disorders with neurological impairment frequently involving the white matter. Moreover, the most frequent childhood white matter disease, X-linked adrenoleukodystrophy, is a peroxisomal disorder. During the past decade advances in imaging techniques have enabled the identification of peroxisomes within the myelin sheath, especially close to nodes of Ranvier. Although the function of myelin peroxisomes is not solved yet on molecular level, recently acquired knowledge suggests a central role for these organelles in axo-glial metabolism. This review focuses on the biology of myelin peroxisomes as well as on the pathology of myelin and myelinated axons that is observed as a consequence of partial or complete peroxisomal dysfunction in the brain. © 2013 The Author. Published by Elsevier Masson SAS. All rights reserved.

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