Although the brain is our most complex organ, the ways to treat it have historically been rather simple.

Typically, surgeons lesioned (damaged) a structure or a pathway in the hope that this would “correct the imbalance” that led to the disease. Candidate structures for lesioning were usually found by trial and error, serendipity or experiments in animals.

While performing one such surgery in 1987, French neurosurgeon Alim-Louis Benabid noticed that the electrical stimulation he performed to locate the right spot to lesion had effects similar to the lesion itself.