Hypnosis and inhibition as viewed by Heidenhain and Pavlov.

About 1880, Rudolf Heidenhain, then Professor of Physiology and Histology at the University of Breslau, experimentally studied hypnotic phenomena. Heidenhain explained hypnosis physiologically, in terms of cortical inhibition. Subsequently, I.P. Pavlov, who in 1877 and again in 1884 was Heidenhain's student at Breslau, encountered hypnotic phenomena during conditional reflex experiments. In 1910, Pavlov described hypnotic states and explained them (as had Heidenhain three decades earlier), in terms of partial inhibition of the cortex. As the concepts of inhibition and excitation are cornerstones of Pavlov's theory of higher nervous activity, it is of historical interest to search for influences that led Pavlov to incorporate the concept of inhibition into his theory. It is most likely that Pavlov first encountered the concept of central inhibition in the 1860s when reading I.M. Sechenov's The Reflexes of the Brain (1863/1866) and that the importance of the concept was augmented by Heidenhain's use of it in explaining hypnotic phenomena.