[Dendrites, neurons and simulation models].

Abstract

The dendritic tree, this morphologically remarkably structured and typically diversified portion of the neuron reveals gradually its till recently little known complex functional possibilities. The size of the dendritic membrane participates in the latter similarly as their morphological pattern and their electronic structure which has a marked effect also due to its passive cable properties on the spread and interaction of potential changes on the membrane. Moreover the presence of a complex, differentiated mosaic of ion channels of different types provides dendrites with non-linearities with a wide scope of dynamic phenomena and active properties. The dendritic membrane can e.g. actively reinforce signals proceeding along the thin dendrite fibres and may make the development of action potentials or their retrograde movement from the membrane of the cell body possible. The possible operations above the spatial and temporal structures of signals equipped by differently located excitation and inhibition synapses are enriched by the action of ions entering via ion channels into the cell when the membrane potential changes. Manifestations of neuroplasticity lend these properties further temporal and functional dimensions. The neuron is no longer a one-way polarized and passive transmitter of synaptic input signals four output action potentials; it is a complicated non-linear hierarchic dynamic system with possible complex temporal and spatial analogue signal transformations in dendritic structures. New findings are the result of the cooperative use of empirical and theoretical procedures based on the morphophysiological methods with a high differentiating capacity and the methodology of studies of dynamic systems and computer simulation.