Linking brain dynamics, deep brain stimulation and human parkinsonian tremor
Freitag, 16.5.08, 11:15-12:15, Raum 404, Eckerstr. 1
The use of deep brain stimulation to alleviate motor symptoms caused by neurodegenerative disorders such as Parkinson's disease has become a standard therapeutic strategy over the last 10 years. This procedure provides a symptomatic relief of symptoms.\n However one limiting factor in the development of improved stimulation protocols is our uncomplete understanding of the physiological mechanisms underlying deep brain stimulation. \n In the present study, results from a computational model and experimental findings are discussed around a common possible physiological mechanism for the effects of deep brain stimulation. We propose that stimulation-induced functional decoupling (SIFD) of neurons in the subthalamic nucleus may be responsible for improvement in motor function. Furthermore we attempt to validate SIFD at the micro- meso- and macro-scopic scales using simulation and experimental results.
Neural modulation with weak electrical fields: a prototype for continuous feedback control
Mittwoch, 28.5.08, 17:15-18:15, Raum 404, Eckerstr. 1
Low frequency (f<<100Hz) electrical fields can be used to polarize pyramidal neurons along their dendrite-soma axis and thereby reversibly modulate their response to natural input. When instrumented carefully this stimulation can be done without interrupting neural recordings and with minimal recording artifact. Therefore stimulation can be programmed as a continuous feedback response to ongoing activity. I'll discuss our earlier work controlling network behavior in brain slices, and our recent work developing and testing a prototype feedback device for chronic seizure control.
Freitag, 30.5.08, 11:15-12:15, Raum 125, Eckerstr. 1
Optimale Stopp-Probleme bei Modellunsicherheit
Freitag, 13.6.08, 11:15-12:15, Raum 404, Eckerstr. 1
We develop a theory of robust optimal stopping problems with multiple priors. Applications are given for problems in Operations Research, Microeconomics, and Finance.
Methods of Cardiovascular Physics and their Clinical Applicability
Donnerstag, 26.6.08, 17:15-18:15, Raum 404, Eckerstr. 1
The number of patients suffering from cardiovascular diseases increases\nunproportionally high with the increase of the human population and\naging, leading to very high expenses in the public health system.\nTherefore, the challenge of cardiovascular physics is to develop\nhigh-sophisticated methods which are able to, on the one hand,\nsupplement and replace expensive medical devices and, on the other hand,\nimprove the medical diagnostics with decreasing the patient’s risk.\nCardiovascular physics – which interconnects medicine, physics, biology,\nengineering, and mathematics – is based on interdisciplinary\ncollaboration of specialists from the above scientific fields and\nattempts to gain deeper insights into pathophysiology and treatment\noptions. This paper presents some recently developed methods and their\nclinical applicability.\nMethods of cardiovascular physics are used to analyze heart rate, blood\npressure and respiration to detect changes of the autonomous nervous system.\n\nData driven modeling analysis and synchronization analysis and their\napplications to heart rate, blood pressure and respiration in healthy\nsubjects and in patients with different diseases are presented. It is\nshown that the use of nonlinear approaches brings a significant\nimprovement of fitting compared to linear models. Several\ntransformations, e.g. functions of interaction between blood pressure\nand heart rate, are highly similar within the individual groups, but\nsignificant different among the groups.\n\nWe show that these data analyses and modeling methods lead to\nsignificant improvements in different medical fields.\n\n\n[1] Wessel N, Malberg H, Bauernschmitt R, Schirdewan A, Kurths J,\nNonlinear additive autoregressive model-based analysis of short-term\nheart rate variability, Med Biol Eng Comput 2006, 44: 321-330.\n\n\n[2] Penzel T, Wessel N, Riedl M, Kantelhardt JW, Rostig S, Glos M,\nSuhrbier A, Malberg H, Fietze I, Cardiovascular and respiratory dynamics\nduring normal and pathological sleep. Chaos 2007, 17: 015116.\n\n\n[3] Riedl M, Suhrbier A, Malberg H, Penzel T, Bretthauer G, Kurths J,\nWessel N, Modeling the Cardiovascular System Using a Non-linear Additive\nAutoregressive Model with Exogenous Input, Phys Rev E 2008, in press.
Freitag, 11.7.08, 11:15-12:15, Raum 404, Eckerstr. 1
Stochastische Simulation von Zugbahnen tropischer Wirbelstürme
Freitag, 11.7.08, 11:15-12:15, Raum 404, Eckerstr. 1
Die Kosten tropischer Wirbelstürme treffen die (Rück-) Versicherungswirtschaft jedes Jahr in der Höhe von vielen Milliarden US-Dollar. Entscheidend für die Gefährdungseinschätzung bei Versicherern sind vor allem die Verläufe der Zugbahnen der Wirbelstürme. Insbesondere sind die sogenannten Landfallpositionen, d.h. diejenigen Orte, an denen die über dem Meer entstandenen Stürme auf Land treffen, von Interesse, sowie die Windgeschwindigkeiten, die dabei im Sturm erreicht werden. Das in diesem Vortrag vorgestellte stochastische Modell (siehe Rumpf et al. (2007,2008)) wurde daher entwickelt, um die Verläufe der Sturmzugbahnen und der zugehörigen Windgeschwindigkeiten zu beschreiben. Zudem ermöglicht es die Simulation von großen Anzahlen \nkünstlicher, aber wirklichkeitsnaher Zugbahnen, was eine verbesserte Gefährdungseinschätzung in betroffenen Gebieten ermöglicht.\n\nDa für zukünftige Gefährdungseinschätzungen auch der Klimawandel und evtl. hieraus resultierende Änderungen in Anzahl, Verhalten und/oder Intensität tropischer Wirbelstürme von zentraler Bedeutung sind, wurden im Rahmen der Modellierung auch potentielle Unterschiede zwischen Wirbelsturmdaten aus verschiedenen Klimaphasen untersucht. Dabei wurden signifikante strukturelle Unterschiede z.B. bei den von den Landfallpositionen gebildeten Punktmustern detektiert.
Freitag, 25.7.08, 11:15-12:15, Raum 404, Eckerstr. 1