Meeting Abstract

S7-1.3.1  Jan. 6  Form and Function of Identified Insect Motoneurons DUCH, Carsten; Arizona State University

Understanding complex neural circuitry requires an understanding of the functions of its basic components - individual neurons. A single neuronís dendritic tree may receive thousands of input synapses. Input integration and computation are strongly affected by synapse distributions, dendritic shape and active conductances. We ask two questions: First, do specific rules exist for dendritic architecture, synapse distribution, and ion channel distribution within complex dendritic trees to ensure behaviorally adequate firing output? Second, what are the developmental mechanisms to create complex dendritic trees with all proteins at the correct sites? We address these questions in holometabolous insects, like Manduca and Drosophila, because structure, physiology and function of identified neurons are modified in parallel during metamorphosis, allowing for studies that directly relate single neuron modifications to developmental changes in behavioral function. We analyze dendritic structure and synapse distribution by combining high resolution confocal microscopy, precise 3-D dendritic reconstruction and novel co-localization analysis tools. We find that stage-specific rules exist for dendritic shape and synapse distribution. Multi-compartment models test the impact of these rules for spatio-temporal synaptic input integration. Developmental mechanisms for establishing dendritic architecture are tested by genetic and electrophysiological manipulations, showing that various changes in the activity patterns of individual neurons affect their architecture in different ways. Finally, behavioral experiments indicate that altered structure and excitability of individual neurons in a motor network affect behavioral performance. A future challenge will be to integrate the different levels of analysis to create a comprehensive framework for understanding physiology and architecture of single neurons in the context of behavioral output.