Authors have fifty years long experience with psychostereotactic surgery. On the bases of 209 operations of different types of mentally ill patients, authors built their own physiological conception of the central nervous system function. The new conception is described using block operators of thinking at the level of hypothalamus, limbic system, and neocortex in the hierarchic order. The basic physiological hypothalamic block contains two operators: stimulus evaluation and decision to act. Both operators together form reasonable, objective substantiation of thinking, which is transformed into psychological, subjective description at higher cerebral levels. New operator is added to the block diagram at the level of the limbic system: the choice of response base on experience stored in the high capacity memory. Vast neocortical memory creates a model of the individual world and it enables a new operator to be involved: prediction of the future events. Thinking, originally based on concrete images, is using abstract terms, subjected to the principles of grammar. Physiological basis of thinking enables the convergence of subjective and objective.

        Key words: physiology of thinking, memory, evaluation of stimulus, choice, prediction, decision