Transcript Neural Network of C. elegans is a Small

Neural Network of C. elegans is
a Small-World Network
Masroor Hossain
Wednesday, February 29th, 2012
Introduction to Complex Systems
Background on C. elegans
• It’s a transparent nematode (roundworm).
• The hermaphrodite version has a simple
nervous system comprising about 302
neurons.
• It’s neural network is completely mapped.
• The pattern of connectivity portrays smallworld network characteristics.
Recall
• The characteristic path length L is defined as
the number of edges in the shortest path
between two vertices, averaged over all pairs
of vertices.
• The clustering coefficient C measures the
degree to which nodes in a graph tend to
cluster together - how close neighbors are to
being a clique.
Procedure for Measuring C – from class
Random Rewiring Procedure
• p = 0 represents regularity (no edge)
• p = 1 represents disorder (clique)
• n = 20 and k = 4
Random Rewiring Procedure
• For C. elegans, an edge/link joins two neurons
if they are connected by a synapse or gap
junction.
• There are n = 282 nodes and k = 14 edges.
NetLogo Models
Cumulative Distribution of Outgoing
and Incoming Neural Connections
Questions?