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- S. Schönknecht,
C. Duch, M. Scholz, and K. Obermayer. Electrophysiological Multi
Compartment Models of the Insect Motoneuron MN5 at Different Stages of
Development.
.
In Soc. Neurosci. Abstr. 28, 2002.
During the metamorphosis of Manduca sexta, MN5 changes from a slow
larval crawling motoneuron into a fast adult flight motoneuron. This
postembryonic change in behavioral function is accompanied by drastic changes
in active and passive membrane properties and in dendritic architecture
[Duch, Levine, 2000; Libersat, Duch, 2002]. In this study we performed
electrophysiological multi compartment models of the MN5 at different
developmental stages, based on a quantitative metric analysis
[Libersat,Duch]. The models result from three dimensional reconstructions of
the motoneurons from confocal images [Schmitt S.,et.al,2000]. We extract a
skeleton and the diameters of the MN5 by means of our reconstruction method
(AMIRA modules) and used these preprocessed data in GENESIS environment. We
investigate, how changes in total and mean dendritic length, surface area and
number of nodes could be responsible for changes in these excitability.
Currently, the simulations focus on validating our model with the following
biological experiments: First, does the model account for changes in membrane
potential that result from various current injections into the soma? Second,
does the model account for the differences in the shape of antidromically and
orthodromically evoked action potentials as measured by intracellular
recording from the soma and from the axo-dendritc junction. Following
necessary adjustments and validation of our model, we aim to address the
functional role of the structural changes for the observed lower excitability
of the adult motoneuron as compared to the larval motoneuron.
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