Oliver Sacks

The famed neurologist talks to Fresh Air about how grief, trauma, brain injury, medications and neurological disorders can trigger hallucinations -- and about his personal experimentation with hallucinogenic drugs in the 1960s.

The famed neurologist talks to Fresh Air about how grief, trauma, brain injury, medications and neurological disorders can trigger hallucinations — and about his personal experimentation with hallucinogenic drugs in the 1960s.

Neurologist Oliver Sacks is famous for his case studies of people with neurological disorders that cause unusual problems with perception. In The Mind's Eye, Sacks turns to himself, explaining how an eye tumor affected his vision and perception of the world.