This is the readme for the model associated with the paper:

Zheng M, Friesen WO, Iwasaki T (2007) Systems-level modeling of
neuronal circuits for leech swimming.  J Comput Neurosci 22:21-38

Abstract:

This paper describes a mathematical model of the neuronal central
pattern generator (CPG) that controls the rhythmic body motion of the
swimming leech. The systems approach is employed to capture the
neuronal dynamics essential for generating coordinated oscillations of
cellmembrane potentials by a simple CPG architecture with a minimal
number of parameters. Based on input/output data from physiological
experiments, dynamical components (neurons and synaptic interactions)
are first modeled individually and then integrated into a chain of
nonlinear oscillators to form a CPG.We showthrough numerical
simulations that the values of a few parameters can be estimated
within physiologically reasonable ranges to achieve good fit of the
data with respect to the phase, amplitude, and period. This parameter
estimation leads to predictions regarding the synaptic coupling
strength and intrinsic period gradient along the nerve cord, the
latter of which agrees qualitatively with experimental observations.

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This archive contains matlab files that simulate the model for leech
swimming CPG that we developed and reported in the above paper.

The main file is "mainrun.m" and all the other files are called in
it. By default, it simulates the CPG model and plots the membrane
potentials (Fig 3b)



and their phase relations (for example Fig. 6):



These files were supplied by Ted Iwasaki, University of Virginia