The behavior of the summary activity is learned on the proposed model
of neuronal net, taking into account the data of the neuronal interact
ions in Ca-3 hippocampus. The summary activities existence of the own
oscillations frequency, depending on the synaptic connection weights i
s found. The hypothesis of this phenomena role on the theta-activity g
enesis in the hippocampus is proposed. The change of own oscillations
under the influence of the external rhythmic excitation, coming on the
net is investigated.