Anatomy and Physiology of Children and Adolescents - M. R. Sapin 2007

Nervous System (General Outline of the Structure and Development of the Nervous System)
Central Nervous System
Higher Nervous Activity — Qualitative Characteristics of Human Higher Nervous Activity

In the first signaling system, all forms of behavior are based on the direct perception of reality and reactions to immediate (natural) stimuli. Humans perceive the external world through The activity of the first signaling system. Consequently, the analysis and synthesis of concrete signals, objects, and phenomena of the external world that make up the first signaling system are common to both animals and humans.

In the course of Human Development, an "extra addition" to Brain function mechanisms emerged. This is the second signaling system of reality, the specific stimulus of which is the word endowed with meaning—a word that denotes objects and phenomena of the surrounding world. I.P. Pavlov defined the second signaling system of reality as the neural processes occurring in the cerebral hemispheres As a result of perceiving signals from the surrounding world in the form of verbal designations of objects and phenomena of nature and society. A word is perceived by a person as heard (Auditory Analyzer), written (visual analyzer), or spoken (motor analyzer). In all cases, these stimuli are united by the meaning of the word. Words acquire meaning through The formation of strong connections in the Cerebral Cortex between the excitation centers arising from specific objects of the surrounding world and the excitation centers arising from the articulation of words that denote those specific objects or actions. As a result of such connections, words can replace a concrete environmental stimulus and become its symbol.

The Emergence of the second signaling system introduced a new principle into human brain activity. The word, acting as a signal of signals, makes it possible to Abstract oneself from concrete objects and phenomena. The Development of verbal signaling made generalization and abstraction possible, which finds expression in phenomena characteristic of humans—thought and concepts.

The ability to think through abstract concepts and images expressed through spoken or written words made the emergence of abstract-generalized thinking possible.

Thus, the human second signaling system serves as the foundation for strictly human verbal-logical thinking, the basis for forming knowledge about the surrounding world through verbal abstractions, and the cornerstone of human consciousness.