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Simulation of motoneuron morphology in three dimensions. I. Building individual dendritic trees
Author(s) -
Marks William B.,
Burke Robert E.
Publication year - 2007
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.21418
Subject(s) - fractal dimension , tree (set theory) , fractal , geometry , dimension (graph theory) , morphology (biology) , trajectory , topology (electrical circuits) , biological system , computer science , mathematics , physics , biology , combinatorics , mathematical analysis , paleontology , astronomy
We have developed a computational method that accurately reproduces the three‐dimensional (3D) morphology of individual dendritic trees of six cat alpha motoneurons. The first step was simulation of trees with straight branches based on the branch lengths and topology of actual trees. A second step introduced the meandering, or wandering, trajectories observed in natural dendritic branches into the straight‐branch tree simulations. These two steps each required only two parameters, one extracted from the data on actual motoneuron dendrites and the other adjusted by comparing simulated and observed trees, using measurements that were independent of the model specifications (i.e., emergent properties). The results suggest that: 1) there is a somatofugal “tropism” (a bias introduced by the environment that affects the trajectory of dendritic branches) that tends to constrain the lateral expansion of alpha motoneuron dendrites; and 2) that most of the meandering of natural dendritic branches can be described by assuming that they are fractal objects with an average fractal dimension D of about 1.05. When analyzed in the same way, the dendrites of gamma motoneurons showed no evidence of a similar tropism, although they had the same fractal dimension of branch meandering. J. Comp. Neurol. 503:685–700, 2007. Published 2007 Wiley‐Liss, Inc.