Aristides Leão

Aristides de Azevedo Pacheco Leão (August 3, 1914 – December 14, 1993 in Rio de Janeiro) was one of the most important Brazilian biologists and scientists, one of the founders of the Biophysics Institute of the Federal University of Rio de Janeiro and the discoverer of cortical spreading depression, an electrophysiological phenomenon of the central nervous system, which received his name.

Leão was born to an intellectual family in Rio de Janeiro. He started studying medicine at the University of São Paulo, but had to interrupt it, due to a bout of tuberculosis. Under the influence of his uncle, Antonio Pacheco Leão, who was the director of the Botanical Gardens of Rio de Janeiro, he decided instead to follow a research career and went to the United States to study further. There he obtained a masters (1942) and a doctorate (1943) in physiology at the Harvard Medical School, with an experimental investigation of epilepsy in the cerebral cortex of rabbits. In collaboration with his supervisors, Arturo Rosenblueth and Hallowell Davis, he analyzed the cycle of excitability of cortex neurons (nerve cells) after the convulsive phenomena, and was the first to identify the important phenomenon of a decrease of the excitability, spread in increasing circles around the initial focus, which he named spreading depression. The phenomenon was named Leão's wave and brought him great attention after this work was published in 1944 in one of the main neurophysiology journals. For the rest of his life, Dr. Leão became one of the most cited neuroscientists in the world, and his original paper is considered one of the classics in the field.

Upon returning to Brazil, he continued his experiments with spreading depression, in the department of physiology of the medical school of the University of Brazil (presently the Federal University of Rio de Janeiro). Already in 1947 he published his first international paper on a research developed entirely in his new Brazilian lab, which was put together with great difficulty due to the lack of resources and specialized equipment. Some of his lifelong colleagues, such as Dr. Hiss Martins Ferreira joined him at that time. In the intervening years he added a great number of his students to the group, such as Drs. Romualdo José do Carmo, Gilberto de Oliveira Castro and others.

Together with Prof. Carlos Chagas Filho (1910–2000), another influential neurophysiologist and biophysicist, Dr. Leão founded the Laboratory of Biophysics, which later became the world-famous Institute of Biophysics, a great cradle of two generations of Brazilian scientists and a center of excellence in neurophysiological research.

Dr. Leão was also an important and influential scientific leader. He was for 15 years the president of the Brazilian Academy of Sciences and a member of the scientific council of the Brazilian National Research Council (CNPq) for many years.

He was a gentle, calm and systematic man, with outstanding wit and culture, very much respected and loved by his colleagues and students. He was also an accomplished amateur naturalist and devoted ornithologist, specialized in tropical birds. He died of respiratory failure when he was 79 years old, in Rio de Janeiro.