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BP: Fachverband Biologische Physik

BP 23: Cell Motility and Migration (in vitro and in vivo)

BP 23.1: Hauptvortrag

Donnerstag, 29. März 2007, 14:00–14:30, H43

The Physics of Neuronal Growth — •Timo Betz, Daniel Koch, and Josef Käs — Institut for Soft Matter Physics, University of Leipzig, Germany

The correct development of the central nervous system requires accurate and reliable neuronal network formation, a process accomplished by a highly dynamic structure at the tip of a growing neurite, called the growth cone. To find its proper target, each growth cone integrates chemical and mechanical signals, and converts these signals into changes of its active polymeric cytoskeleton. To understand these fundamental growth processes, we quantified the physical properties of a growth cone, like traction forces, viscoelastic properties and actin dynamics, and found that growth cones show unique features with respect to other motile cell types.

We show that bistable stochastic fluctuations between growth and retraction phases determine the direction of neuronal growth, and that these fluctuations are dominated by bistable modes of actin polymerization. Furthermore, the viscoelastic properties of the growth cone are combined with the measured actin dynamics to calculate the active internal and external forces generated by the growth cone. Integrating these data suggests that growth cones utilize physical processes like stochastic signal amplification and unique mechanical properties to build an organism's intricate nervous system. Moreover, our measurements provide the base to understand the complex interplay between actin polymerization, active internal forces and substrate adhesion that finally results in nerve regeneration and neuronal network formation.