[
International Worm Meeting,
2003]
The ultimate goal of the present work is to determine pathways of neuronal signal from sensory neurons to motoneurons in occasion of native responses of C. elegans. The fundamental hypothesis is that the pathways consists of highly multiple synaptic connection among interneurons. The McCulloch-Pitts equation is employed to find out sequence of much synaptic connection from each sensory neuron. Although the McCulloch-Pitts equation cannot be used for simulation of propagation of neuronal signal without knowledge about physical parameters within it, it is useful for the present purpose. The point of the algorithm is ; (i) threshold of menbrain potential is replaced by an integer s which is independent of the neuron and (ii) the coupling coefficient between a pair of neurons is replaced with number of synapses between them. When a sensory neuron is always excited, a stationary distribution of excited neurons is realized. Excited neurons in the stationary state are connected to the sensory neuron by pathways which consist of synaptic connection of multiplicity larger than s. A neuron, which is connected with more than one excited neurons, is also excited when the sum of multiplicity of joined synapses are larger than s. A plan of the neuronal circuit is constructed from neurons, which are excited for s more than six, and synapses connecting them. Interneurons are classified into three groups. Three elementary motions of the worm are defined in terms of motoneurons which are simultaneously excited and its behavior in occasion of native responses is combination of such elementary motions. The number of synapses have been counted using the database constructed by our research group. It is translation from the sketch of neurons published by White et al.. into a digital form.