It is crucial to determine the effects on the network level of a modulation of intrinsic membrane properties. The role calcium-dependent potassium channels, K(Ca), in the lamprey locomotor system has been investigated extensively. Earlier experimental studies have shown that apamin, which affects one type of K(Ca), increases the cycle duration of the locomotor network, due to effects on the burst termination. The effects of apamin were here larger when the network had a low level of activity (burst frequency 0.5 to 1 Hz) as compared to a higher rate (> 2 Hz). By using a previously developed simulation model based on the lamprey locomotor network, we show that the model could account for the frequency dependence of the apamin modulation, if only the K(Ca) conductance activated by Ca2+ entering during the action potential was altered and not the K(Ca) conductance activated by Ca2+ entering through NMDA channels. The present simulation model of the spinal network in the lamprey can thus account for earlier experimental results with apamin on the network and cellular level that previously appeared enigmatic.
Bibliographical noteFunding Information:
We thank the reviewers and the action editor for their useful and thorough comments on this work. We are also indebted to Drs. Lennart Brodin, Abdel El-Manira, Russell Hill, David Parker, and Peter Wallén for valuable comments on the manuscript and Dr. Örjan Ekeberg for supplying the SWIM simulation software (see http://www.nada.kth.se/sans/). Patriq Fagerstedt provided useful help on the design of Figures 4 and 9. This work was supported by the Medical Research Council (Project No. 3026), the Swedish Natural Science Research Council (Project No. B-AA/BU03531), the Swedish National Board for Industrial and Technical Development, NUTEK (Project No. 8425-5-03075), and the Swedish Society for Medical Research.
- Computer simulation
- K(Ca) channels
- Relaxation oscillator
- Spinal circuits
ASJC Scopus subject areas
- Sensory Systems
- Cognitive Neuroscience
- Cellular and Molecular Neuroscience