Neuron Doctrine and Conditional Reflexes at the XIV International Medical Congress of Madrid of 1903

Abstract

There is a long tradition of holding meetings to present new ideas or discoveries that help in transforming our world in different areas of science and industry. One of these meetings was the 14th International Medical Congress held in Madrid in 1903. In the Anatomy and Physiology Sections presentations included two important milestones for the development of neuroscience: Cajal’s neuron doctrine and Pavlov’s theory of conditional reflexes. Both discoveries shared some ideas in common: a) both considered that “the organism” should be studied as a whole, b) developed methods to study the phenomena in vivo, thus bypassing the restrictions imposed by the classic anatomy and physiology; and c) searched the elementary unit that allowed an objective study of psychic activity. For Cajal neurons were individual cells and in them were based brain and mental activity therefore, Cajal described them in a poetic way, as the “butterflies of the soul”. Pavlov regarded the conditional reflex as the basic "psychic” (or psychological) phenomenon. These discoveries made by Pavlov and Ramón y Cajal (but also other colleagues such as Golgi or Sherrington) are the result of collective work and individual effort, and behind their studies we find a brilliant intelligence, a strong will and tenacity and the ability to develop technical innovation. The concepts that underlie the neuron doctrine of Cajal and the conditioned reflexes of Pavlov pioneered the study of the nervous system, mental processes and behavior which has guided the further psychological research and the development of neuroscience.