[Characteristics of the hippocampal formation functioning during wakefulness and paradoxical sleep].

In view of the available published data concerning various concentration of neuromodulators in the brain during paradoxical sleep and wakefulness and the evidence for the influences of neuromodulators on efficiency of synaptic inputs to hippocampal neurons it is concluded that during paradoxical sleep, increase in concentrations of acetylcholine, cortisol, and dopamine and simultaneous decrease in serotonin and noradrenaline levels could synergistically lead to essential depression of efficacy of synaptic transmission in the polysynaptic pathway through the hippocampus (i.e. in the perforant path to dentate gyrus, from the dentate gyrus to CA3 area, from CA3 to CA1 area and from CA1 to the subiculum) but potentiation of the efficacy of the perforant input to pyramids of CA1 and CA3 areas and increase in efficacy of associative connections between CA3 neurones. The specified changes in functioning of the hippocampal loop can underlie differences in storing and extraction of information from memory during paradoxical sleep as compared to wakefulness.