[Mechanisms of the formation of long-periodicity oscillations in activity in nerve nets. Nets with pre- and postsynaptic inhibition].

The role of presynaptic and postsynaptic processes in formation of the long-term (hundreds of milliseconds) activity of neuronal networks was analyzed by the mathematical simulation model. The long-term activity of networks with presynaptic inhibition was discontinued due to the depolarization of the neuronal terminals that achieved its critical level and to significant suppression of the effectiveness of synaptic interaction. The long-term activity of networks with postsynaptic inhibition was discontinued because of the activation of inhibitory neurons exerting strong hyperpolarizing effects on other neurons of the networks. Synchronization of neuronal discharges was important in achievement of the critical level by terminal depolarization or inhibitory postsynaptic processes that interrupted the network activity. Properties of neuronal networks with presynaptic and postsynaptic inhibition were compared with those of uniform neuronal networks (with a positive feedback between neurons only). It is concluded that introduction of the additional negative feedback circuits in a form of presynaptic or postsynaptic inhibition contributes to improvement of reliability and accuracy of the mechanism which terminates the network activity.