Dendritic voltage dependent conductances increase the excitatory synaptic response and its postsynaptic inhibition in a reconstructed alpha-motoneuron: A computer model

Mammalian spinal monosynaptic Ia EPSP and its postsynaptic reciprocal depol arizing inhibition was studied using NEURON simulator in a morphologically and physiologically characterised alpha -motoneuron. Low g(Na) and g(K) loc ated at the dendrites greatly enhanced EPSPA+N maximal amplitude and its re ciprocal inhibition. A small area of active dendrite is sufficient for obta ining the maximal increase in excitatory response for each g(Na). EPSP peak is monotonically augmented by raising g(Na), whereas inhibition is enhance d until a specific g(Na) and a further increase diminishes the inhibitory e ffect. Computer simulations performed at four additional alpha -motoneurons yielded similar results. (C) 2001 Elsevier Science B.V. All rights reserve d.