%0 Journal Article
%T Search for computational modules in the C. elegans brain
%A Markus Reigl
%A Uri Alon
%A Dmitri B Chklovskii
%J BMC Biology
%D 2004
%I BioMed Central
%R 10.1186/1741-7007-2-25
%X Our statistical analysis reveals that some inter-connectivity patterns containing two, three and four (but not five) neurons are significantly over-represented relative to the expectations based on the statistics of smaller inter-connectivity patterns.Over-represented patterns (or motifs) are candidates for computational modules that may perform stereotypical functions in the C. elegans nervous system. These modules may appear in other species and need to be investigated further.There is little doubt that neurons are elementary building blocks of the nervous system [1]. It is less clear, however, whether multi-neuron modules (smaller than invertebrate ganglia or vertebrate nuclei and cortical columns) can be meaningfully defined, either anatomically [2] or physiologically [3]. The existence of such multi-neuron modules would greatly simplify the description of nervous system structure and function. An example of such simplification can be found in electrical engineering. An electronic circuit is often represented in terms of modules such as operational amplifiers, logical gates and memory registers rather than as a wiring diagram showing each transistor, resistor and diode. However, unlike electrical engineers who designed these modules themselves, neurobiologists did not design the brain, and evolution rarely leaves records of its experimentation. Therefore, if multi-neuron modules have indeed evolved they need to be discovered.In this paper, we search for anatomically defined multi-neuron modules in the Caenorhabditis elegans nervous system. We choose C. elegans as a model organism because its wiring diagram is largely known, including the identities of all 302 neurons and most synapses between them [4-6]. Our approach follows the reasoning developed previously in the context of gene regulation and other networks [7,8]. If a certain multi-neuron module performs some stereotypical function it may appear in the nervous system repeatedly. Therefore, search for multi-
%U http://www.biomedcentral.com/1741-7007/2/25