Topological and statistical analysis of 3-D reconstructions of axon collaterals

This is the first statistical metrical, topological. and model-oriented study of the spatial properties of collaterals of the primary afferent and reticulo-spinal axons, which monosynaptically innervate motoneurons of the lumbar segments of the frog spinal cord. It has been shown that ramification of both types: of the collaterals is significantly asymmetrical. They differ from each other in the degree of asymmetry, which may be used for their topological classification. Spatial distribution of the synaptic boutons of these collaterals corresponds to a compound Poisson scheme, which means that the contacts are aggregated in clusters within 3-D space. We also showed that this distribution is fiducially related to the distribution of the expectation time for contacts measured as the distance along the collateral from a site of the collateral origin to a contact.