Information Technology Reference
In-Depth Information
Fig. 11.1.
Sketch of C. elegans anatomy.
behavior, at the molecular and cellular levels [5, 6]. It has been extensively studied
to understand particular biological phenomena, with the expectation that discover-
ies made in this organism will provide insight into the workings of other organisms.
It is one of the usually called model organisms. In particular, model organisms
are widely used to explore potential causes and treatments for human disease when
human experimentation would be unfeasible or unethical. This approximation is
supported by the fact of common descent of all living organisms, and the con-
servation of metabolic and developmental pathways and genetic material over the
course of evolution. In fact, this goal was a primary motivation behind the devel-
opment of C. elegans as an experimental organism 40 years ago. Yet it has proven
surprisingly dicult to obtain a mechanistic understanding of how the C. elegans
nervous system generates behavior, despite the existence of a \wiring diagram" that
contains a degree of information about neural connectivity unparalleled in any or-
ganism. Studying model organisms can be informative, but generalizations should
be carefully considered.
The structural anatomy of C. elegans is basically that of a cylinder around
1 millimeter in length and 0.1 millimeter in diameter, see Fig. 11.1. In the following,
we will use the common hypothesis of study of a one dimensional entity. We are
interested in its neuronal system, in particular in the position along the body of the
dierent neurons and its interconnections. The current work uses the public data
found in [7]. The construction of this data set started with the work by Albertson
et al., and White et al. [8, 9], and has been contributed by many authors since
then, in the multimedia project Wormatlas [7]. The particular wiring diagram we
use was revised and completed by Chen et al. [3] using other valuable sources [11,
12]. The wiring information we have used is structured in four parts: connectivity
data between neurons, neuron description, neuron connections to sensory organs
and body muscles, and neuronal lineage. The architecture of the nervous system
of C. elegans shows a bilaterally symmetric body plan.
With a few exceptions,
