Max Planck Institute for Dynamics and Self-Organization -- Department for Nonlinear Dynamics and Network Dynamics Group
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BCCN AG-Seminar

Tuesday, 23.09.2008 17 c.t.

Activity and chemoaffinity in the development of neural circuitry

by Dr. Dmitry Tsigankov
from Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA

Contact person: Theo Geisel

Location

Seminarraum Haus 1, EG

Abstract

In developing brain, neurons are capable of connecting to each other with high precision, thus forming accurate circuitry. We present a theoretical and computational analysis of the mechanisms that result in the development of precise neural connectivity. The study is based on the system of retinal ganglion cells that project to superior colliculus (optic tectum) in midbrain where they form topographic map of the visual world. Both chemoaffinity and electrical activity of the connecting neurons contribute to the development of topography. We propose the description based on the energy function of the system of developing neurons which unifies these different contributions from nature and nurture. Within this framework we explain the abnormal connectivity that is observed in various mutant animals. We also show that the combination of chemoaffinity and Hebbian activity-dependent interactions can result in the formation of ocular dominance patterns and find the period of this structure. In the computational model we study the branch dynamics of developing arbors of axons and dendrites that result in the most effective mechanism of the circuitry formation. We obtain that optimal branching strategies are synaptotropic and that they differ for axons and dendrites of developing neurons.

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