Dynamics of Functioning of Voltage-Operated Ion Channels in the Dendrite Plasma Membrane

Abstract

Dendrites provide the analysis and transmission of numerous and variable synaptic signals to the soma and axon hillock of nerve cells. According to generally accepted concepts, generation of action potentials (APs) is initiated precisely in the latter cell compartment. The problem of the dynamics of functioning of voltage-operated ion channels, whose properties are extremely variable, is closely related to the integrative functions of the dendrites. These channels are involved in information transmission and its translation to other domains of the neuron. The biophysical properties of dendrite ion channels and the density of their distribution in many cases differ significantly from the analogous indices in other compartments of the neuron. Moreover, the expression of ion channels and their properties in different branches of the dendrite tree of one and the same neuron can be considerably dissimilar. Such phenomena as back-propagation of APs via the dendrites and the possible initiation of local APs in some branches of the dendrite tree are significantly involved in the induction of synaptic plasticity; these processes may result in either augmentation of synaptic potentials or their suppression. Local synthesis of definite proteins is also realized in the dendrites; this process is controlled by synaptic inputs and postsynaptic activity. The possibility of performance of a few integrative functions by separate dendrites of a single neuron is at present intensely discussed; earlier, such functions were postulated to be a prerogative of complex neuronal networks.