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We describe a strongly biologically motivated artificial neural network approach to model neurogenesis and synaptic turnover as it naturally occurs for example in the hippocampal dentate gyrus (DG) of the developing and adult mammalian and human brain. The results suggest that cell proliferation (CP) has not only a functional meaning for computational tasks(More)
This study is concerned with synaptic reorganization in local neuronal networks. Within networks of 30 neurons, an initial disequilibrium in connectivity has to be compensated by reorganization of synapses. Such plasticity is not a genetically determined process, but depends on results of neuronal interaction. Neurobiological experiments have lead to a(More)
Between the extreme views concerning ontogenesis (genetic vs. environmental determination), we use a moderate approach: a somehow pre-established neuronal model network reacts to activity deviations (reflecting input to be compensated), and stabilizes itself during a complex feed-back process. Morphogenesis is based on an algorithm formalizing the(More)
Plasticity of synaptic connections plays an important role in the temporal development of neural networks which are the basis of memory and behavior. The conditions for successful functional performance of these nerve nets have to be either guaranteed genetically or developed during ontogenesis. In the latter case, a general law of this development may be(More)
Postnatal development of the K+-stimulated release of [3H]GABA in rat cortex slices was compared to the density of Gray type 2 synapses (which correlate with GABAergic synapses in rat cortex). The [3H]GABA release system develops earlier than the inhibitory synapses which suggests that, at least in the young cortical tissue, a large part of the release(More)
High affinity binding of [3H]gamma-aminobutyric acid (GABA) to membrane-containing homogenates prepared from rat cerebral cortex (neonatal or adult) or from adult rat superior cervical ganglion (SCG) was tested for sensitivity to baclofen, bicuculline and several other analogues of GABA. Since no major differences were found between the tissues free of(More)
scenario is akin to the magnetic furnace model proposed by Axford and McKenzie (14–16) and to ideas invoking reconnection of mesoscale loops (38, 39). We adopt from the furnace model the idea that reconnection plays a major role, as it will release plasma, set free magnetic energy, and produce Alfvén waves. However, our model of the nascent solar wind is(More)
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