Dr. Roman Borisyuk
University of Plymouth, UK
A crucial question in computational neuroscience relates to understanding the architecture of neuronal connections in the circuit which provides some particular brain function. As a rule the biological connection architecture is unknown and a typical approach is to use some standard connection scheme. A more promising approach is to learn from a biological system how neurons organize their connectivity. In this study we collaborate with neurobiologists (Prof. Alan Roberts, University of Bristol) to discover the neuronal architecture of the spinal cord of the tadpole, which can provide neural activity patterns corresponding to swimming behavior of the tadpole.
A new mathematical model of axon growth is developed which includes both difference equations and stochastic variables. We find optimal parameter values by fitting the model to experimentally measured characteristics of the axon. The fitted model generates axons for different neuron types which are similar to the experimentally measured axons. Taking into account experimental data on the distribution of neuronal cell bodies along the spinal cord and the dorso-ventral distribution of dendrites we generate a biologically realistic architecture of the whole tadpole spinal cord: we grow axons and as they pass dendrites of other cells they make synaptic contacts with a prescribed probability. A preliminary study of the electrophysiological properties of the generated architecture with Morris-Lecar neurons shows that the model can generate electrical activity corresponding to the experimentally observed swimming pattern of the tadpole in a broad range of parameter values.
References
W.-C. Li, T. Cooke, B. Sautois, S. R. Soffe, R. Borisyuk, and A. Roberts. Axon and dendrite geography predict the specificity of synaptic connections in a functioning spinal cord network. Neural Develop, 2(17):1-18, Oct 2007.
. Borisyuk, T. Cooke, and A. Roberts. Stochasticity and functionality of neural systems: Mathematical modelling of axon growth in the spinal cord of tadpole. BioSystems, in press, available online, 2008.
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