The latest episode of In Our Time discusses the development and evolution of neuroscience (here). Although the focus is primarily on the present, historical aspects are included as well.
In the mid-19th century a doctor had a patient who had suffered a stroke. The patient was unable to speak save for one word. The word was ‘Tan’ which became his name. When Tan died, the doctor discovered damage to the left side of his brain and concluded that the ability to speak was housed there.
This is how neuroscience used to work — by examining the dead or investigating the damaged — but now things have changed. Imaging machines and other technologies enable us to see the active brain in everyday life, to observe the activation of its cells and the mass firing of its neuron batteries.