The generalized Carnot principle introduced by Brillouin provides a link between negentropy and information, but does not take into account the information stored in the brain, which is clearly excluded by the author. Further step in the generalization of Carnot's principle, which includes information turnover in the brain was accomplished by Kepiński in his theory of the metabolism of energy and information. According to Schrödinger, life processes require a supply of negentropy rather than energy stored in the food, more precisely, e.g., in glucose utilized by the brain, since energy is conserved, whereas negentropy is dissipated. The information (communication) channel transmits maximum information when the band width of the transmitted frequency is limited, and much less information when the restriction concerns the transmitted power, or energy. This can explain a considerable decrease in the information metabolism observed in depressive patients, whose life dynamics and, consequently, the amount of energy available for information metabolism is severly lowered. Thus, the fall in information metabolism is more pronounced in depression than in not too late phases of schizophrenia. As appears from Fonberg's studies the amygdaloid nucleus is responsible for the life dynamics. In different types of neuron code change is a significant parameter, which was so strongly stressed by Kepiński. Other problems discussed in the paper include: selection of information and its structural localization, localization of particular phases of information metabolism and their phylogenetic significance.