Seminars of the Focus Area Complex Systems

Prof. Dr. C. Beta, Prof. Dr. K. Dethloff, Prof. Dr. R. Engbert, Prof. Dr. M. Holschneider, Prof. Dr. W. Huisinga, Prof. Dr. Ralf Metzler, Prof. Dr. A. Pikovsky, Prof. Dr. S. Reich, Prof. Dr. M. Rosenblum, Prof. Dr. G. Rüdiger, Prof. Dr. T. Scheffer, Prof. Dr. F. Scherbaum, Prof. Dr. J. Selbig, Prof. Dr. F. Spahn

Seminar

Speaker: Martin Falcke, Mathematical Cell Physiology Max Delbrück Centre for Molecular Medicine

Title: Random but reliable: Information transmission by spike sequences of IP3-induced Ca2+ signaling

Time: Mon, May 16, 2011, 16:15

Place: bldg 28, room 0.108

Abstract:
Ca2+ is a universal second messenger in eucaryotic cells transmitting information through sequences of concentration spikes. A prominent mechanism to generate these spikes involves Ca2+ release from the endoplasmic reticulum (ER) Ca2+ store via IP3-sensitive channels. Puffs are elemental events of IP3-induced Ca2+ release through single clusters of channels. Intracellular Ca2+ dynamics are a stochastic system, but a complete stochastic theory has not been developed yet. As a new concept, we formulate the theory in terms of interpuff interval and puff duration distributions, since unlike the properties of individual channels, they can be measured in vivo. Our theory reproduces the typical spectrum of Ca2+ signals like puffs, spiking and bursting in analytically treatable test cases as well as in more realistic simulations. We find conditions for spiking and calculate interspike interval (ISI) distributions. Signal form, average ISI and ISI distributions depend sensitively on the details of cluster properties and their spatial arrangement. In difference to that, the relation between the average and the standard deviation of ISIs does not depend on cluster properties and cluster arrangement, and is robust with respect to cell variability. It is controlled by the global feedback processes in the Ca2+ signaling pathway (e.g. via IP3-3-kinase or ER depletion). That relation is essential for pathway function, since it ensures frequency encoding despite the randomness of ISIs and determines the maximal spike train information content. Hence, we find a division of tasks between global feedbacks and local cluster properties which guarantees robustness of function while maintaining sensitivity of control of the average ISI.

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Past NLD Seminars (1994-2007) & (2008 ...)

Students' seminar: Theoretical Physics, PIK, Modeling & TSA Berlin-Potsdam-Colloquia: PhysGesellschaft Berlin, TU Berlin, Pro Physik, AIP, AEI, MPI-KGF, GFZ, HMI, PIK, AWI, Max Planck Institute for the History of Science, Mathematik, DPG Disputationen, & Vorschau UP

Udo Schwarz, Zentrum für Dynamik komplexer Systeme,
Universität Potsdam, Campus Golm Karl-Liebknecht-Str. 24, 14476 Potsdam, building 28, room 2.107
Phone: (+49-331) 977-1658, Fax : (+49-331) 977-1045

Email: Udo.Schwarz AT uni-potsdam.de

DFG SFB 1294

DFG Sonderforschungsbereich 1294 Data assimilation

DFG SPP 1488

DFG Schwerpunktprogramm 1488 Planetmag


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