The author tries to present in a brief article an integrated view of different forms of neuronal oscillations. He describes their effect on the genesis of physiological and pathological EEG activity and on the function of the thalamo-cortical and septoippocampal reverberation circuit with regard to the relationship of these reverberation circuits to cognitive functions in REM, NONREM sleep and vigilance. From this anatomical and physiological aspect the author tries to define consciousness with regard to the phylo- and ontogenetic aspect of this phenomenon.

        Key words: acetylcholine, activation system, electroencephalogram, transient calcium channels, neuromodulations, neuronal oscillations, reverberation circuits, septo-hippocampal circuit, sleep, thalamo-cortical circuit, consciousness