Topic description:
Neurons have a wide range of dendritic morphologies whose functions are largely unknown. We used an optimization procedure to find neuronal morphological structures for two computational tasks: First, neuronal morphologies were selected for the task of summing excitatory synaptic potentials (EPSPs) linearly. Second, structures were selected that distinguished the temporal order of EPSPs. The solutions resembled the morphology of real neurons. In particular the neurons optimized for linear summation electrotonically separated their synapses, as found in avian nucleus laminaris neurons. Neurons optimized for spike order detection had primary dendrites of significantly different diameter, as found in the basal and apical dendrites of cortical pyramidal neurons. The automated mapping between neuronal function and structure introduced allows a large catalog of computational functions to be built indexed by morphological structure.

Biographical note:
Klaus Stiefel (b. Klagenfurt, 1972) was a Postdoctoral Fellow in the Computational Neurobiology Laboratory (headed by Terry Sejnowski), The Salk Institute, San Diego, CA, from July 2002 to August 2006. He studied Biochemistry and Microbiology at the University of Vienna (1991-98), was an exchange student at the University of California, San Diego (1995-96), and did his PhD work on "LTP and LTD in the Visual Cortex of the Rat" in Wolf Singer's lab at the Max PIanck Institute for Brain Research, Frankfurt am Main (1998-2002); PhD in Zoology, University of Vienna, 2002. Starting November 2006, he will be Principal Investigator of the Theoretical and Experimental Neurobiology Unit at the Okinawa Institute of Science and Technology. Publications Stiefel KM, Tennigkeit F, Singer W (2005) Synaptic plasticity in the absence of backpropagating spikes of layer II inputs to layer V pyramidal cells in rat visual cortex. European Journal of Neuroscience 21(9): 2605-10. Stiefel KM, Wespatat V, Tennigkeit F, Singer W (2005) Phase dependent sign changes of GABAergic synaptic input explored in-silicio and in-vitro. Journal of Computational Neuroscience 19(1): 71-85. Schmidt H, Stiefel KM, Racay P, Schwaller B, Eilers J (2003) Mutational analysis of dendritic Ca2+ kinetics in rodent Purkinje cells: role of parvalbumin and calbindin D28k. Journal of Physiology 551(1): 13-32. Stiefel KM, Wespatat V, Singer W, Tennigkeit F (2001) A computational model of the interaction of membrane potential oscillations with inhibitory synaptic input in cortical cells. Neurocomputing 38-40: 389-95.