There are two sorts of criteria of consciousness--objective and subjective ones. They are the ability for operating with the knowledge which could be addressed to other people in the abstract form and the feeling of 'ego' as a 'host' of these actions, respectively. These two signs of consciousness are provided with the mechanism based on the synthesis in the brain structures of different kinds of information: sensory information, the data extracted from the memory and the signals from the centers of emotions and motivation. As a result of this synthesis, the sense of 'ego' arises and the message designated for others is determined. A significant role in the informational synthesis is played by dynamic cortical structures--foci of interaction. In perception they are localized predominantly in the projectional cortex, in thinking and in the associative areas. Realization is closely connected with communication and appearance of the interaction foci in the verbal zones of the left hemisphere. Pavlov (1951), in his program lecture in Madrid early in the present century, said that he saw the final aim of his study in the revealing of the mechanism and the inner vital sense of human consciousness. It is important, that Pavlov placed the words 'mechanism' and 'vital sense' near each other, i.e., he considered that the sense of consciousness would be realized through revealing its mechanism. This insight attracts our attention now, when the problem on consciousness mechanism is in scientific plans and the search for the meaning of life by the end of the twentieth century, one full of dramatic events, acquires a special value.