Andreas Schierwagen

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The small G protein p21Ras is a critical molecular switch for relaying neurotrophic actions and is essential for normal functioning and plasticity of the nervous system. In this study, the morphogenetic effects of p21Ras were investigated on neurons in vivo. Morphological changes of layers II/III and Vb commissural pyramidal neurons of the primary(More)
Morphological data on two classes of neurons from mammalian midbrain have quantitatively been analyzed for dendritic shape parameters. Their frequency distributions were used to optimize the parameters of a dendritic growth model which describes dendritic morphology by a stochastic growth process of segment branching. The model assumes randomness with(More)
A non-uniform equivalent cable model of membrane voltage changes in branching neuronal trees with active ion channels has been developed. A general branching condition is formulated, extending Rall's 3/2 power rule for passive dendritic trees so that non-uniform cable segments can be treated. The theoretical results support the use of the dendritic profile(More)
This paper is focused on quantification (morphometry) and modeling of neuronal morphological complexity. First, computer-aided methods for reconstruction, processing, and analysis of raw morphological data are reviewed. Then, topological and metrical measures are touched upon. Fractal measures (together with the extension of multiscale fractal dimension)(More)
Experimental data derived from two classes of superior colliculus neurons*deep layer neurons (DLNs) and super"cial layer neurons (SLNs)*have been used to study the in#uence of dendritic anatomy on synaptic input processing. Anatomical measures of dendrites were "rst determined. Compartmental neuron models (3 of each class) were built to estimate passive(More)
Theories of how the brain computes can be differentiated in three general conceptions: the algorithmic approach, the neural information processing (neurocomputational) approach and the dynamical systems approach. The discussion of key features of brain organization (i.e. structure with function) demonstrates the self-organizing character of brain processes(More)
Dendritic complexity of deep layer cat superior colliculus neurons has been studied by means of a stochastic model for dendritic outgrowth with randomly branching and elongating neurites. Branching probabilities are assumed to depend on the position and the number of segments in the growing tree. It is demonstrated that the shape properties of model(More)
Dendritic morphology is the structural correlate for receiving and processing inputs to a neuron. An interesting question then is what the design principles and the functional consequences of enlarged or shrinked dendritic trees might be. As yet, only a few studies have examined the effects of neuron size changes. Two theoretical scaling modes have been(More)