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Neural Network of the Nematode C. elegans


"Database of Synaptic Connectivity of C. elegans"
is available with Online Tool



Photo by Prof. Oka (Keio Univ.)


What is C. elegans?
Caenorhabditis elegans (C. elegans) is a phylum Nematoda. It is 1.5mm in length and lives in the soil. Because of its transparent body, ontogenesis is observed by Nomarski-type differential interference contrast microscopy as it is alive. C. elegans has necessary minimum systems as an animal, such as epidermis, nervous system, muscular system, digestive organ and reproductive organ. Most of worms are hermaphrodite, and only 0.2% of them are male. The hermaphrodite C. elegans consists of 959 somatic cells. The 959 somatic cells represent most of the major differentiated tissue types including neurons (302 cells), muscles (111 cells), intestine (34 cells) and epidermis (213 cells).
On C. elegans, the followings have been determined.
  • Cell lineage (1977[1], 1983[2])*1
  • Structure and synaptic connectivity of the nervous system (1976[3], 1986[4])*2
  • Genome sequence (1998[5])*3
Furthermore, over 1,500 mutants are identified. Response to mechano-stimuli, chemotaxis, thermotaxis, effects of laser ablation of selected neurons, and aging gene are also investigated[6,7]. In addition, a database of the synaptic connectivity is available for numerical study[9]. Taking advantage of the above mentioned investigations, we study on the neural network of C. elegans.

Mathematical Formulation for a Partial Neural Network
To understand neural information processing in C. elegans, we usually employ a colsed partial neural network because of a large number of the degree of freedom in the whole neural network. The influence of the remaining neurons of C. elegans is completely neglected. However, there is no guarantee that a result in the closed partial neural network is consistent with that in the whole (real) neural network since neural information processing is a highly nonlinear phenomenon. Therefore effective formulations for a partial neural network of C. elegans are developed on the basis of statistical physics and information science[8].


*1. The complete lineage map of every single cell in the body of the adult.

*2. The neural connectivity (chemical synapse, gap junction) and the functional classification of neurons (sensory neuron, inter-neuron, motor neuron) are summarized in a database[9].

*3. The gemome size is about 97Mbp (97106 base pairs). The number of chromosomes is six.


Reference
  1. J. E. Sulston and H. R. Horvitz: "Post-embryonic Cell Lineages of the Nematode Caenorhabditis elegans", Developmental Biology, 56 (1977) 110-156.
  2. J. E. Sulston, E. Schierenberg, J. G. White and J. N. Thomson: "The Embryonic Cell Lineage of the Nematode Caenorhabditis elegans", Developmental Biology, 100 (1983) 64-119.
  3. D. G. Albertson and J. N. Thomson: "The Pharynx of Caenorhabditis elegans", Phil. Trans. R. Soc. London, B 275 (1976) 299-325.
  4. J. G. White, E. Southgate, J. N. Thomson and S. Brenner: "The Structure of the Nervous System of the Nematode Caenorhabditis elegans", Phil. Trans. R. Soc. London, B 314 (1986) 1-340.
  5. The C. elegans Sequencing Consortium: "Genome Sequence of the Nematode C. elegans: A Platform for Investigating Biology", Science, 282 (1998) 2012-2018.
  6. W. B. Wood (Ed.): "The Nematoda Caenorhabditis elegans", (Cold Spring Harbor Laboratory Press, New York, 1988).
  7. D. L. Riddle, T. Blumenthal, B. J. Meyer and J. R. Priess (Eds): "C. elegans II", (Cold Spring Harbor Laboratory Press, New York, 1997).
  8. Y. Iwasaki and S. Gomi: "Stochastic formulation for a partial neural circuit of C. elegans", Bulletin of Mathematical Biology, 66 (2004) 727-743. [Full Text via ScienceDirect]
  9. K. Oshio, Y. Iwasaki, S. Morita, Y. Osana, S. Gomi, E. Akiyama, K. Omata, K. Oka and K. Kawamura: "Database of Synaptic Connectivity of C. elegans for Computation", Technical Report of CCeP, Keio Future, No.3 (Keio University, 2003).


Related International Conference
  1. Y. Iwasaki, S. Gomi, Y. Osana, K. Oshio, S. Morita and K. Oka: "Numerical Study on Excitatory and Inhibitory Pathways in Neural Network of C. elegans", Third East Asian Biophysics Symposium (Kyongju, Korea, 2000).
  2. S. Gomi, Y. Iwasaki and Y. Osana: "Study of Excitatory and Inhibitory Synaptic Connections in Neural Circuit for Touch-induced and Tap Responses", The 2nd Japanese C. elegans meeting (Tokyo, Japan, 2000).
  3. Y. Iwasaki and S. Gomi: "Stochastic method to predict synaptic signs in a partial neural network of C. elegans", The 3rd Japanese C. elegans meeting (Nagoya Univ., Japan, 2002).
  4. K. Oshio, S. Morita, Y. Osana, Y. Iwasaki, S. Gomi, K. Omata, E. Akiyama and K. Oka: "Revision of synaptic connectivity database", The 3rd Japanese C. elegans meeting (Nagoya Univ., Japan, 2002).
  5. Y. Iwasaki and S. Gomi: "Statistical formulations for a partial neural circuit of C. elegans", The 14th International C. elegans Conference (UCLA, USA, 2003).
  6. K. Kawamura, Y. Funabashi, K. Oshio, S. Morita, Y. Osana, Y. Iwasaki, S. Gomi, K. Omata, E. Akiyama and K. Oka: "Neuronal Circuit and Native Responses of C. elegans", The 14th International C. elegans Conference (UCLA, USA, 2003).
  7. K. Kawamura, K. Oshio, Y. Iwasaki, S. Morita, Y. Osana, S. Gomi, K. Omata and E. Akiyama: "Anatomical Data of Synaptic Connectivity of C. elegans are Almost Perfectly Self-contained", 2004 East Asia Worm Meeting (Awaji Island, Japan, 2004).
  8. Y. Iwasaki: "How to model and study a partial neural circuit of C. elegans?", The 15th International C. elegans Conference (UCLA, USA, 2005).
  9. Y. Iwasaki: "Effective Modeling of a Partial Neural Network of C. elegans: Theory and Application", The 2nd International Conference on Brain-Inspired Information Technology (BrainIT 2005), (Kitakyushu, Japan, 2005).
  10. Y. Iwasaki: "Neural Circuit and Behavioral Criteria of C. elegans", Fifth East Asian Biophysics Symposium (Okinawa, Japan, 2006).
  11. Y. Iwasaki: "Numerical study of habituation to touch stimulation and synaptic plasticity", The 16th International C. elegans Conference (UCLA, USA, 2007).
  12. Y. Iwasaki: "Analysis of noise robustness in neural circuit of C. elegans", The 17th International C. elegans Conference (UCLA, USA, 2009).
  13. M. Kuramochi, K. Sakata, R. Shingai and Y. Iwasaki: "Neuronal model including Ca2+ dynamics in C. elegans", The 4th East Asia C. elegans Meeting (Tokyo, Japan, 2010).
  14. R. Shingai, H. Takahashi, Y. Iwasaki, K. Sakata, T. Wakabayashi and T. Ogurusu: "Computer simulation for neuronal network of C. elegans", The 4th East Asia C. elegans Meeting (Tokyo, Japan, 2010).
  15. M. Kuramochi and Y. Iwasaki: "Quantitative Modeling of Neuronal Dynamics in C. elegans", 17th International Conference on Neural Information Processing (Sydney, Australia, 2010); in "Neural Information Processing: Theory and Algorithms" Lecture Notes in Computer Science, Vol. 6443, pp. 17-24 (Springer-Verlag, 2010).
  16. M. Kuramochi, K. Sakata, R. Shingai and Y. Iwasaki: "Dynamical model variables, calcium imaging and design of C. elegans neuron", 7th Asian Biophysics Association Symposium (New Delhi, India, 2011).



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