Theoretical model of slow-wave membrane potential oscillations in molluscan neurons.

A model describing slow-wave membrane potential oscillations observed in molluscan neurons has been developed. It takes into account non-inactivating calcium and Ca-dependent potassium currents found experimentally in these neurons. This model successfully describes the form of the experimental potential wave as well as the dependence of the oscillatory behaviour of molluscan neurons on the extracellular concentration of Ca2+ and K+ ions. By changing different parameters of the model I was able to obtain three patterns of the electrical activity of molluscan neurons. These are as follows: silent neurons with the resting potential ranging from -49 to -53 mV; neurons which demonstrate a slow-wave oscillatory activity with an interval between 12 and 17 s; and neurons with repetitive firing activity. The possible interaction between these three patterns of the electrical activity is considered and its neurophysiological significance is discussed. It was shown, in the framework of the model developed, that a neuron can switch from one pattern to another by changing any parameter of the model. It is most likely that such alteration in the electrical neuronal activity is connected with a change in intracellular adenosine 3',5'-cyclic monophosphate content affecting both the magnitude of the calcium conductance and the intracellular level of Ca2+ ions.