Answer: Ramachandran is known for his work in understanding the human brain from a behavioral perspective.
Vilayanur Subramanian Ramachandran is an Indian born neuroscientist and professor currently teaching at the University of California San Diego (UCSD) department of psychology. His specialty is understanding neurological illnesses, in particular phantom limb pains, synesthesia, and body image disorders. He has written a number of neurology and neuroscience focused books, including Phantoms in the Brain and The Encyclopedia of the Human Brain. He has also given TED talks related to his research.
Phantom limb pain
When a person loses a part of their body, they may experience the sensation of pain where that lost organ once was. For example, people who lose an arm can perceive the sensation of arm pain. Ramachandran notes that this pain can also exist for visceral, internal organs as well, such as women who have had a hysterectomy who experience cramping. This perception of pain (even though there is no organ to send pain information into the brain) is called phantom pain. The prevalence of phantom pain is estimated to be as high as 80% among amputees (Chronic phantom and stump pain among American veterans: Results of a survey).
Ramachandran has worked to develop psychological strategies which allow a person to overcome and suppress that phantom pain. One of these strategies is called a mirror box. With it, it is possible to conduct mirror therapy, also called mirror visual therapy.
The mirror box is a cheap piece of equipment, consisting of a set of mirrors. In Ramachandran’s mirror visual therapy, a person with a missing limb is seated at a table. A mirror is placed in the middle of the body so that the intact limb is reflected to where the missing limb would be located. The patient is told to visualize that the missing limb is replaced by the mirror image of the intact limb. Then, they are instructed to move their intact limb and imagine that they are doing the same motions with their missing limb. The brain is quickly fooled by this illusion, and this trick causes the phantom pain to disappear.
What causes phantom pain is still unknown. One theory put forward by Ramachandran suggests that when a person loses a limb, the somatosensory cortex rewires itself in an unusual way to where the sensory tracts originating in the missing limb ultimately project into different areas. They demonstrated their theory by gently touching the faces of amputees, who report that their missing limb was being touched ("Perceptual correlates of massive cortical reorganization").
Mirror therapy can also help patients improve their motor performance in stroke-related paralysis.
A major advantage of mirror box therapy is that it is much cheaper than similar “limb replacement” strategies, such as virtual reality therapy or robotics. Also, mirror boxes are better at relieving phantom pain compared to these high-tech strategies.
Synesthesia
Synesthesia is a perceptual disorder that is characterized by atypical detection of stimuli when a different sensory system is activated. People with synesthesia therefore experience a cross mapping of their senses. For example, someone with synesthesia may see colors when they hear certain sounds, or see shapes when they taste food (as described by Dr. Cytowic in The Man Who Tasted Shapes)
One of the most common forms of synesthesia is called grapheme-color synesthesia. For these people, they see individual letters or numbers as having a certain color associated with them. For example, the letter A often appears as red for these grapheme-color synesthetes.
Ramachandran was one of the first people to theorize as to the neural foundation of why a person experiences synesthesia. His theory suggested that there was an unusual miswiring of brain structures. Using an imaging technique called functional magnetic resonance imaging (fMRI), Ramachandran demonstrated that the visual cortices of people with synesthesia are more active than the visual cortex of people without synesthesia (Individual Differences among Grapheme-Color Synesthetes: Brain-Behavior Correlations).
Capgras delusion
Capgras delusion is a rare psychological condition that can appear in schizophrenia, after a brain injury, or neurodegenerative disease. In patients with Capgras delusion, they believe that someone close to them has been replaced by an imposter. They may become suspicious of the person.
Ramachandran put forward the theory that there is a breakdown in facial processing that causes these people to misidentify close friends or family. Ramachandran found that they are still able to recognize the person by voice. For example, if you put the patient on the phone with the person, they will recognize them by their voice. If they hear the person talking with them from another room, the patient will have no difficulty, despite their Capgras delusion. In Ramachandran’s view, these findings hint that the connectivity between auditory cortex and memory is unaffected in patients with Capgras delusion.
Ramachandran proposed a few strategies to help patients overcome their Capgras delusion. One of them is to use auditory cues to help strengthen the association between the person and the face. If the person with the Capgras delusion were talking to a person from another room, they might continue the conversation as they enter in the same room, thus connecting the audio cue with the face.
Mirror neurons
Mirror neurons are specialized cells that exist in the motor, sensory, and parietal cortices. They are observed to fire under two conditions: when an organism is performing some action, and when that organism sees someone else perform that same action. Because of these firing properties, they “mirror” the stimuli that the organism experiences.
Ramachandran put forth the idea that activity of these mirror neurons underlie all behaviors of mankind. He believes that empathy towards others is affected by the activity of these mirror neurons. Through his research with autistic patients, he developed the “Broken Mirrors” theory of autism, which suggests that the activity of the mirror neurons is suppressed in autism. They experience mu wave suppression in the EEG traces. This theory is highly controversial.