Vilayanur Subramanian Ramachandran (born August 10, 1951) is an Indian-American neuroscientist and psychologist distinguished for his research in behavioral neurology and visual psychophysics. He is a distinguished professor in the Department of Psychology at the University of California, San Diego (UCSD), where he directs the Center for Brain and Cognition.

Ramachandran obtained an M.B.B.S. from Stanley Medical College in Chennai, India. He later earned a Ph.D. from Trinity College at the University of Cambridge in 1978, where he studied visual perception. Before joining UCSD as an assistant professor of psychology in 1983, he spent two years at Caltech as a research fellow.

Ramachandran's research encompasses a wide array of topics in behavioral neurology and cognitive neuroscience:

• Phantom Limbs: He is well-known for his investigations into phantom limbs, theorizing a connection between this phenomenon and neural plasticity in the adult human brain. His work led to the development of mirror therapy as a treatment for phantom limb pain.
• Mirror Therapy: Ramachandran invented the mirror box, a device utilizing a mirror to create the illusion of movement in a paralyzed or missing limb. This therapy has been shown to reduce phantom limb pain and improve motor control in stroke patients.
• Mirror Neurons: Ramachandran has speculated on the role of mirror neurons in various human mental capacities, including empathy, imitation learning, and language evolution. He proposed that mirror neurons could revolutionize psychology much like DNA revolutionized biology.
• "Broken Mirrors" Theory of Autism: Ramachandran hypothesized that dysfunctional mirror neuron activity might contribute to autism spectrum disorders.
• Synesthesia: He theorized that grapheme-color synesthesia arises from cross-activation between brain regions. His research, using fMRI, found increased activity in color recognition areas of the brain in synesthetes.
• Xenomelia (Apotemnophilia): Ramachandran proposed that apotemnophilia, a rare disorder where individuals desire amputation of a limb, is a neurological condition linked to the right parietal lobe of the brain.
• "Phantom Sex" Theory of Gender Incongruence: Ramachandran theorized that gender dysphoria could be caused by a mismatch between the brain's body image and the external somatic gender.

Ramachandran often employs simple tools like mirrors and stereoscopes in his research, emphasizing intuition and clinical acumen over complex brain imaging technologies.

Ramachandran has received numerous awards and honors, including the Padma Bhushan from the Indian government in 2007 and the "Scientist of the Year" award from the ARCS Foundation in 2014. He has also held fellowships at All Souls College, Oxford, and Stanford University.

• Phantoms in the Brain: Probing the Mysteries of the Human Mind (1998)
• The Tell-Tale Brain: A Neuroscientist's Quest for What Makes Us Human (2010)
• The Emerging Mind (2003)