Dresden 2006 – scientific programme

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DY: Dynamik und Statistische Physik

DY 41: Dynamical Physics in Biological Systems

DY 41.3: Talk

Thursday, March 30, 2006, 10:30–10:45, SCH 251

Neuronal Growth: A Bistable Stochastic Process — •Timo Betz, Daryl Lim, and Josef Käs — Institut for Soft Matter Physics, University of Leipzig, Linnestr. 5, 04103 Leipzig, Germany

During the past decade, modeling biological systems as stochastic processes has given tremendous insight into nature’s working principles at the level of networks, single cells, and molecules. However, the stochastic nature of neuronal growth has hardly been investigated. The basic step in the correct neuronal wiring of a developing organism is the controlled advancement of a highly motile structure, called the growth cone, which is directed by gradients of chemical guidance cues. We report on the first statistical analysis of the stochastic fluctuation of a neuronal growth cone’s leading edge movement. Describing the edge movement with a stochastic process allows inferring a bistable potential from the edge velocity distribution. Using Kramers’ approach to calculate decay rates, an isotropic noise parameter can be determined, which we used to consistently connect the measured edge velocity distribution and the residence time distribution. An according analysis of the growth cone’s motility confirms the model, and predicts that linear changes of the bistable potential might result in the directed growth cone translocation. These results help to understand how the growth cone can detect chemical gradients that are on the order of one molecule across its diameter, even in the highly noisy environment of a developing organism.