The first person who, I think, really developed some kind of insight into what was going on in the brain was the great Spanish neuroanatomist, Santiago Ramón y Cajal, in the 19th century, who used microscopy and special stains that could selectively fill in or render in very high contrast the individual cells in the brain, in order to start to understand their morphologies.
A primeira pessoa que eu acho,  que, de fato, desenvolveu algum insight sobre o que acontecia no cérebro foi o grande neuroanatomista espanhol, Santiago Ramón y Cajal, no século 19, usando microscópio e reagentes especiais, que puderam, seletivamente, preencher ou converter em contraste muito elevado, as células individuais do cérebro, para conseguir entender a morfologia delas.