Accommodation in motoneuron models with passive dendrite: Response to linearly rising currents

Abstract

The biophysical properties of cat motoneuron (MN) models with passive dendrite and different sizes have been extensively tested. However, the behavior of these models in relation to accommodation has not been tested yet. The experimental data reported have shown that MNs accommodate to a very limited degree, exhibiting, in some extension, breakdown of accommodation phenomenon. One possible explanation for the latter behavior would be the presence of persistent sodium conductance. The accommodation can be evaluated by observing threshold latency (TL) curve and the accommodation coefficient ( I/ I 0) s , obtained from the response to linearly rising currents. The simulation results have showed that the models exhibit breakdown of accommodation phenomenon and much similar accommodation coefficients, despite their type: 1.463, 1.456 and 1.418 to S, FR and FF MN models, respectively. According to these data, all the MN models can be classified as slowly accommodating. Our data suggests that accommodation coefficients cannot be associated to the size or to the type of the MN, and persistent sodium conductance might not be necessary to explain breakdown of accommodation phenomenon in MN soma at all.