Physics (1945) at the National School of Medicine of the Federal University of Rio de Janeiro. He was invited by Carlos Chagas Filho, to join the new Biophysics Institute, which was still being organized. His colleagues included Gustavo de Oliveira Castro. Romualdo José do Carmo and , He continued his research into cortical spreading depression. The instruments in his laboratory in Brazil were salvaged discards, but they were so carefully restored that they were always ready for use. Despite discouraging practical limitations, he did not abandon his work and so published his first article in Brazil. His first article on spreading depression, 'Spreading depression of electrical activity in the cerebral cortex,' the phenomenon was given the eponym of his name and called Leão's spreading depression. Leão was director of the institute from 1966 to 1970 and emeritus head of the neurobiology department from 1984 to 1993. He became an associate of the Brazilian Academy of Sciences (1948) and a full member in 1951, and was its vice-president (1955-1957/1965-1967) and president for seven consecutive terms (1967-1981). He was a member of the Deliberative Council at CNPq (1960–74) and then its scientific advisor (1975–84). During the Brazilian military dictatorship, as President of the ABC, he also defended the Revista Brasileira de Biologia (Brazilian Journal of Biology) after its editors were arrested by the regime. While president he also encouraged scientific cooperation between Brazil and other countries. After the cesium leak in Goiânia, in 1988, he became the president of the newly created State Commission of Radioprotection and Nuclear Safety. Between 1985 and 1991 he participated in the Planning and Science and Technology Secretariats of the Presidency of the Republic, as member and president of the Special Followup Group (GEA) of the Scientific Development Support Program (PADCT). After his mandatory retirement, he was named Laboratory Head Emeritus of the Department of Neurobiology of the Carlos Chagas Filho Biophysics Institute, where he remained for nine more years as a CNPq research fellow. Leão's Wave Aristides Leão discovered the phenomenon while working on his thesis at Harvard in 1944. He named the phenomenon "spreading depression", but it became known as "the Leão's wave". The true causes of this depression are not known, but it can be induced by electric shocks. The description of this illness helped in the diagnosis of other diseases such as epilepsy. According to Leão's later investigations, it occurs not only in