Firing Behaviour of a Neurone Model Based on the Afterhyperpolarization Conductance Time Course and Algebraical Summation. Adaptation and Steady State Firing

Abstract F. B aldissera and B. G ustafsson . Firing behaviour of a neurone model based on the afterhyperpolarization conductance time course and algebraical summation. Adaptation and steady state firing. Acta physiol. scand. 1974. 92. 27–47. A preceding paper described the firing behaviour of a neurone model, in which the refractoriness was solely governed by a K conductance process similar to that underlying the afterhyperpolarization in the cat's a‐motoneurones (Baldissera and Gustafsson 1974 b). The present paper describes the firing behaviour of the same model implemented with algebraical summation of the consecutive AHP conductance. For the initial intervals after the onset of constant current the model is well simulating the successive changes in the frequency‐current (f/i) relations and the interspike voltage trajectories found in real motoneurones. The steady state f/i relation of the model can also display an upward deviation from linearity at higher current intensities, i.e. a ‘primary’ and a ‘secondary’ range of firing as described for real motoneurones (Kernell 1965 c). The results are discussed in relation to the terminology describing firing behaviour in motoneurones and to various hypotheses on firing control. It is concluded that the AHP conductance is the decisive factor for determining the f/i relations as well as the interspike voltage trajectories in motoneurones.