Looking back at Jerzy Konorski's book "Integrative Activity of the Brain" 45 years after.

This article presents historical background preceding writing and publication of Jerzy Konorski book "Integrative Activity of the Brain" followed by a short description of the main topics covered in the book. Two new and original contributions of Konorski are presented in detail, his theory of the motivational processes and the organization of the sensory systems in the brain. Those two contributions are then incorporated in the revised theory of the classical and type II conditioned reflexes which constitutes the core of the book. Conclusions point out at some of the ideas which remained valuable for the present day neuroscientists.