(V.B. Kazantsev, A.Yu. Simonov, Yu. V. Zaytsev, M.Galkina, I.A. Metrikin, A.A. Martyanov) Recent studies of neuronal activity have shown that networks of synaptically connected neurons can generate definite spike sequences that repeate with high degree of precision (Ikegaya, 2004). Such sequences can be considered as universal way of internal information representation and encoding. They are formed due to definite signal transmission and transformation functions built in the neuronal networks. The spike sequences can be described using polychromous groups representing pulse trains with a certain distribution of inter-spike interval. This distribution is mainly defined by the axonal delays of signal transmission between synaptically connected neurons (Izhikevich, 2004). The project is devoted to find out dynamical mechanisms of spike sequence formation and stability in small networks of Hodgkin-Huxley neurons with delays of synaptic connections. The possibility of a particular sequence produced by electrical or chemical (for instance, via astrocyte ) signals and its stability due to synaptic plasticity are investigated on the base of the small neuronal group analysis.

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Fig. 1. (а) Schematic of model neuron and (b) spiking pattern generated in model network of Hodgkin-Huxley neurons with excitatory/inhibitory synaptic connections and axonal propagation delays.