Submitted on May 17, 2006
Accepted on February 2, 2007
Roles of ionic currents in lamprey CPG neurons: a modeling study
Mikael E Huss1, Anders Lansner1, Peter Wallén2, Abdel El Manira2, Sten Grillner3, and Jeanette Hellgren Kotaleski4*
1 School of Computer Science and Communication, KTH, Stockholm, Sweden
2 Dept Neuroscience, Karolinska Institute, Stockholm, Sweden
3 Dept Neuroscience, Karolinska Institute, Sweden
4 Dept Neuroscience, Karolinska Institute, Stockholm, Sweden
* To whom correspondence should be addressed. E-mail: jeanette.hellgren{at}ki.se.
The spinal network underlying locomotion in the lamprey consists of a core network of glutamatergic and glycinergic interneurons and has previously been studied experimentally and through mathematical modeling. We present a new and more detailed computational model of lamprey locomotor network neurons, which is based primarily on detailed electrophysiological measurements and incorporates new experimental findings. The model uses a Hodgkin-Huxley-like formalism and consists of 86 membrane compartments containing 12 types of ion currents. One of the goals was to introduce a fast, transient potassium current (Kt) and two sodium-dependent potassium currents, one faster (KNaF) and one slower (KNaS), in the model. The model has both lended support to the interpretation of experimental results and provided predictions for further experimental analysis of single network neurons. For example, Kt was shown to be one critical factor for controlling action potential duration. In addition, the model has been helpful in investigating the possible influence of the slow afterhyperpolarization on repetitive firing during ongoing activation. In particular, the balance between the simulated slow sodium-dependent and calcium-dependent potassium currents has been explored, as well as the possible involvement of dendritic conductances.
