The 2011 TIME 100

Once described as the Marco Polo of neuroscience, V.S. Ramachandran has mapped some of the most mysterious regions of the mind. He has studied visual perception and a range of conditions, from synesthesia (in which viewing black-and-white figures evokes the perception of color) to autism. But Ramachandran, 59, is best known for developing a therapy for phantom-limb pain in which a mirror is used to reflect the intact limb, creating the illusion that the missing one is still there. That persuades the brain that all is well, and the pain subsides. With his simple, creative and innovative ideas, V.S. Ramachandran is changing how our brains think about our minds.

Insel is the director of the National Institute of Mental Health

See TIME's video "V.S. Ramachandran: The 'House' of Neuro-Science."