Vilayanur S. Ramachandran

 

Vilayanur S. Ramachandran MD, PhD

 

 

Vilayanur Subramanian Ramachandran (born 1951) is a neuroscientist known for his work in the fields of behavioral neurology and visual psychophysics. He is the Director of the Center for Brain and Cognition, and is currently a Professor in the Department of Psychology and the Neurosciences Graduate Program at the University of California, San Diego.

Ramachandran is noted for his use of experimental methods that rely relatively little on complex technologies such as neuroimaging. According to Ramachandran, “too much of the Victorian sense of adventure [in science] has been lost.” Despite the apparent simplicity of his approach, Ramachandran has generated many new ideas about the brain.[7] He has been called “The Marco Polo of neuroscience” by Richard Dawkins and “the modern Paul Broca” by Eric Kandel. In 1997 Newsweek named him a member of “The Century Club”, one of the “hundred most prominent people to watch” in the 21st century. In 2011 Time listed him as one of “the most influential people in the world” on the “Time 100” list.  Early life and education

Vilayanur Subramanian Ramachandran (in accordance with some Tamil family name traditions, his family name, Vilayanur, is placed first) was born in 1951 in Tamil Nadu, India. His father, V.M. Subramanian, was an engineer who worked for the U.N. Industrial Development Organization and served as a diplomat in Bangkok, Thailand.Ramachandran spent much of his youth moving among several different posts in India and other parts of Asia. As a young man he attended schools in Madras, Bangkok and England, and pursued many scientific interests, including conchology. Ramachandran obtained an M.B.B.S. from Stanley Medical College in Madras, India, and subsequently obtained a Ph.D. from Trinity College at the University of Cambridge. While a graduate student at Cambridge Ramachandran also collaborated on research projects with faculty at Oxford, including David Whitteridge of the Physiology Department. He then spent two years at Caltech, as a research fellow working with Jack Pettigrew. He was appointed Assistant Professor of Psychology at the University of California, San Diego in 1983, and has been a full professor there since 1998.

Ramachandran is the grandson of Sir Alladi Krishnaswamy Iyer, Advocate General of Madras and co-architect of the Constitution of India.  He is married to Diane Rogers-Ramachandran and they have two boys, Mani and Jaya.

Scientific career

Ramachandran has studied neurological syndromes to investigate neural mechanisms underlying human mental function. Ramachandran is best known for his work on syndromes such as phantom limbs, body integrity identity disorder, and Capgras delusion. His research has also contributed to the understanding of synesthesia. More recently his work has focused on the theoretical implications of mirror neurons and the cause of autism. In addition, Ramachandran is known for the invention of the mirror box. He has published over 180 papers in scientific journals. Twenty of these have appeared in Nature, and others have appeared in Science, Nature Neuroscience, Perception and Vision Research. Ramachandran is a member of the editorial board of Medical Hypotheses (Elsevier) and has published 15 articles there.

Ramachandran’s work in behavioral neurology has been widely reported by the media. He has appeared in numerous Channel 4 and PBS documentaries. He has also been featured by the BBC, the Science Channel, Newsweek, Radio Lab, and This American Life, TED Talks, and Charlie Rose.

He is author of Phantoms in the Brain which formed the basis for a two part series on BBC Channel 4 TV (UK) and a 1-hour PBS special in the USA. He is the editor of the Encyclopedia of the Human Brain (2002), and is co-author of the bi-monthly “Illusions” column in Scientific American Mind.

Ramachandran has recently lamented that science has become too professionalized. In a 2010 interview with the British Neuroscience Association he stated: “But where I’d really like to go is back in time. I’d go to the Victorian age, before science had professionalized and become just another 9–5 job, with power-brokering and grants nightmares. Back then scientists just had fun. People like Darwin and Huxley; the whole world was their playground.”

Human vision

Ramachandran’s early research was on human visual perception using psychophysical methods to draw clear inferences about the brain mechanisms underlying visual processing.

Ramachandran is credited with discovering several new visual effects and illusions; most notably perceived slowing of motion at equiluminance (when red and green are seen as equally bright), stereoscopic “capture” using illusory contours, stereoscopic learning, shape-from-shading, and motion capture. He invented (together with Richard Gregory) filling in of “artificial scotomas” and discovered a new “dynamic noise after effect.” He also invented a class of stimuli (phantom contours) that selectively activate the magnocellular pathway in human vision and that have been used by Anne Sperling, and her colleagues, to evaluate aspects of dyslexia.

Phantom limbs

When an arm or leg is amputated, patients continue to feel vividly the presence of the missing limb as a “phantom limb”. Building on earlier work by Ronald Melzack (McGill University) and Timothy Pons (NIMH), Ramachandran theorized that there was a link between the phenomenon of phantom limbs and neural plasticity in the adult human brain. In particular, he theorized that the body image maps in the somatosensory cortex are re-mapped after the amputation of a limb. In 1993, working with T.T. Yang who was conducting MEG research at the Scripps Research Institute, Ramachandran demonstrated that there had been measurable changes in the somatosensory cortex of several patients who had undergone arm amputations. Ramachandran theorized that there was a relationship between the cortical reorganization evident in the MEG images and the referred sensations he observed in his subjects. He presented this theory in a paper titled “Perceptual correlates of massive cortical reorganization.” Although Ramachandran was one of the first scientists to emphasize the role of cortical reorganization as the basis for phantom limb sensations, subsequent research has demonstrated that referred sensations are not the perceptual correlate of cortical reorganization after amputation. The question of which neural processes are related to non-painful referred sensations has not been resolved.

Mirror visual feedback & Mirror box

Ramachandran is credited with the invention of the mirror box and the introduction of mirror visual feedback as a treatment for a variety of conditions associated with phantom limb pain, stroke, and regional pain syndrome. Several research studies using mirror therapy have produced promising results. However, mirror therapy has produced conflicting results in randomized controlled trials, and the applications of mirror therapy are still under experimental evaluation.

Synesthesia

 

 

Synesthetes who experience color when viewing different symbols may quickly identify the presence of the “triangle” in the left-hand image.

Main article: Synesthesia

Ramachandran has studied the neural mechanisms of synesthesia, a condition in which stimulation in one sensory modality leads to experiences in a second, unstimulated modality. His initial studies focused on grapheme → color synesthesia, in which viewing black and white letters or numbers (collectively referred to as graphemes) on a page evokes the experience of seeing colors. Ramachandran (with then PhD student, Edward Hubbard) showed that some synesthetes were better able to detect “embedded figures” composed of one letter or number (for example a triangle composed of 2s) on a background of another number (for example 5s).

Based on his previous work on phantom limbs, Ramachandran suggested that synesthesia may arise from a cross-activation between brain regions.  Although the idea of cross-connections dates to some of the earliest work on synesthesia, Ramachandran was the first to give this idea a specific anatomical explanation. Ramachandran suggested that grapheme-color synesthesia is the result of increased connectivity between brain areas that are responsible for the perceptual recognition of letters and numbers and colors, perhaps due to genetic factors, given that synesthesia is known to run in families.  Ramachandran theorized that

Different subtypes of number–color synaesthesia…are caused by hyperconnectivity between colour and number areas at different stages in processing; lower synaesthetes may have cross-wiring (or cross-activation) within the fusiform gyrus, whereas higher synaesthetes may have cross-activation in the angular gyrus.

Consistent with this model, Ramachandran’s group found increased activity in color selective areas in synesthetes compared to non-synesthetes using fMRI.  Using MEG, they also showed that differences between synesthetes and non-synesthetes begin very quickly after the grapheme is presented.  However, recent research in the Netherlands (involving 19 grapheme-color synesthetes) demonstrated that synesthesia can be the result of either direct bottom-up cross-activation from grapheme processing areas within the fusiform gyrus, or indirectly via higher-order parietal areas. Tessa van Leeuwen and her colleagues concluded:

To summarize, in this first study of effective connectivity in synesthesia, we established that while the same network of regions is active in different types of synesthesia, individual differences in subjective color experience are determined by altered coupling.

Recently, Ramachandran has also begun investigations of other forms of synesthesia, including number forms and tactile → emotion synesthesia. Ramachandran has helped to advance public awareness of synesthesia by hosting two meetings of the American Synesthesia Association at UCSD in 2002 and 2011.

Conceptual metaphors

Ramachandran has speculated that synesthesia and conceptual metaphors may share a common basis in cortical cross-activation. In 2003 Ramachandran and Edward Hubbard published a paper in which they speculated that the angular gyrus is at least partially responsible for understanding metaphors.

Recent research by Krish Sathian (Emory University) using functional magnetic resonance imaging (fMRI) suggests that conceptual metaphors activate the texture-selective somatosensory cortex in the parietal operculum.  Sathian stated that “I don’t think that there’s only one area for metaphor processing…several recent lines of research indicate that engagement with abstract concepts is distributed around the brain.”  Vilayanur Ramachandran commented that “the authors have paved the way” to study how different brain regions communicate. “This is a very ingenious and elegant approach to the problem.”

Evolution of language

Following Lakoff and Johnson, Ramachandran argues that metaphors are non-arbitrary. Ramachandran and Hubbard suggest that “these rules [of metaphor production] are a result of strong anatomical constraints that permit certain types of cross-activation, but not others.”  Ramachandran has suggested that the evolution of language is the result of three types of non-arbitrary mappings: between sounds and visual shapes (the bouba-kiki effect), sensory-to-motor synesthesia, and motor-to-motor synesthesia (or “synkinesia”).

Mirror neurons

Ramachandran is known for advocating the importance of mirror neurons. Ramachandran has stated that the discovery of mirror neurons is the most important unreported story of the last decade.  (Mirror neurons were first reported in a paper published in 1992 by a team of researchers led by Giacomo Rizzolatti at the University of Parma.) Ramachandran has speculated that research into the role of mirror neurons will help explain a variety of human mental capacities ranging from empathy, imitation learning, and the evolution of language. Ramachandran has also theorized that mirror neurons may be the key to understanding the neurological basis of human self awareness.

Ramchandran has theorized that in addition to motor command mirror neurons there are mirror neurons that are activated when a person observes someone else being touched. In 2008 Ramachandran conducted an experiment in which several phantom arm patients reported feeling touch signals on their phantom arms when they observed the arm of a student being touched. In a 2009 discussion of this theory Ramachandran and Althschuler called these mirror neurons “touch mirror neurons.”

Autism: Pathophysiology

In 1999, Ramachandran, in collaboration with then post-doctoral fellow Eric Altschuler and colleague Jaime Pineda, was one of the first to suggest that a loss of mirror neurons might be the key deficit that explains many of the symptoms and signs of autism spectrum disorders.  Between 2000 and 2006 Ramachandran and his colleagues at UC San Diego published a number of articles in support of this theory, which became known as the “Broken Mirrors” theory of autism. Ramachandran and his colleagues did not measure mirror neuron activity directly; rather they demonstrated that children with ASD showed abnormal EEG responses (known as Mu wave suppression) when they observed the activities of other people. In 2008 Oberman, Ramachandran and Pineda conducted an experiment in which children with ASD showed both normal and abnormal EEG responses depending on their familiarity with people whose actions they were observing.  Oberman and Ramachanran concluded that “The study revealed that mu suppression was sensitive to degree of familiarity. Both typically developing participants and those with ASD showed greater suppression to familiar hands compared to those of strangers. These findings suggest that the Mirror Neuron Systmen responds to observed actions in individuals with ASD, but only when individuals can identify in some personal way with the stimuli.”

Ramachandran’s theory that dysfunctional mirror neuron systems(MNS) play an important role in autism remains controversial. In his 2011 review of The Tell-Tale Brain, Simon Baron-Cohen, Director of the Autism Research Center at Cambridge University, states that “As an explanation of autism, the [Broken Mirrors] theory offers some tantalizing clues; however, some problematic counter-evidence challenges the theory and particularly its scope.”

Recognizing that dysfunctional mirror neuron systems cannot account for the wide range of symptoms that are included in autism spectrum disorder (ASD), Ramachandran has theorized that childhood temporal lobe epilepsy and olfactory bulb dysgenesis may also play a role in creating the symptoms of ASD. In 2010 Ramachandran stated that “The olfactory bulb hypothesis has important clinical implications” and announced that his group would undertake a study “comparing olfactory bulb volumes in individuals with autism with those of normal controls.”

Rare neurological syndromes

Apotemnophilia

In 2008 Ramachandran, along with David Brang and Paul McGeoch, published the first paper to theorize that apotemnophilia is a neurological disorder caused by damage to the right parietal lobe of the brain.  This rare disorder, in which a person desires the amputation of a limb, was first identified by John Money in 1977. Building on Ramachandran’s previous work identifying representations of body image in the brain, they argued that this disorder stems from a neural body image that is incomplete. Hence the person sees their limb as a foreign appendage that is outside their body. Ramachandran has extended this theory to suggest that anorexia nervosa may be a body image disorder that has its basis in neurological representations of the body, rather than an appetite disorder of the hypothalamus.

Capgras delusion

In collaboration with then post-doctoral fellow, William Hirstein, Ramachandran published a paper in 1997 in which he presented a theory describing the neural basis of Capgras delusion, a delusion in which family members and other loved ones are thought to be replaced by impostors. Previously, Capgras delusion was attributed to a disconnection between facial recognition and emotional arousal. Ramachandran and Hirstein presented a more specific structural explanation that argued that Capgras delusion might be the result of a disconnection between the “fusiform face area”, a region of the fusiform gyrus involved in face perception, and the amygdala, which is involved in the emotional responses to familiar faces. Additionally, based on their model and the specific responses of the patient they examined (a Brazilian man who had sustained a head injury in a traffic accident), Ramachandran and Hirstein proposed a general theory of memory formation. They speculated that a person suffering from Capgras delusion loses the ability to form a taxonomy of memories and hence they can no longer manage memories effectively. Instead of a continuum of memories that constitute a unified sense of self, each memory takes on its own categorical sense of self.

Alternating gender incongruity (AGI)

In 2012, Case and Ramachandran reported the results of a survey of bigendered individuals who experience involuntary alternation between male and female states. Case and Ramachandran hypothesized that gender alternation may reflect an unusual degree (or depth) of hemispheric switching, and the corresponding suppression of sex appropriate body maps in the parietal cortex. They stated that “we hypothesize that tracking the nasal cycle, rate of binocular rivalry, and other markers of hemispheric switching will reveal a physiological basis for AGI individuals’ subjective reports of gender switches… We base our hypotheses on ancient and modern associations between the left and right hemispheres and the male and female genders.”

Awards and honors

Ramachandran was elected to a visiting fellowship at All Souls College, Oxford (1998–1999). In addition he was a Hilgard visiting professor at Stanford University in 2005. He has received honorary doctorates from Connecticut College (2001) and the Indian Institute of Technology, Madras (2004). Ramachandran received the annual Ramon y Cajal award (2004) from the International Neuropsychiatry Society, and the Ariens-Kappers medal from the Royal Netherlands Academy of Sciences for his contributions to Neuroscience (1999). He shared the 2005 Henry Dale Prize with Michael Brady of Oxford, and, as part of the award was elected an honorary life member of the Royal institution for “outstanding research of an interdisciplinary nature”.  In 2007, the President of India conferred on him the third highest civilian award and honorific title in India, the Padma Bhushan. In 2008, he was listed as number 50 in the Top 100 Public Intellectuals Poll.

Invited plenary lectures

Ramachandran has presented numerous plenary lectures around the world. He gave the Decade of the Brain lecture at the 25th annual meeting of the Society for Neuroscience in 1995, the D.O. Hebb Lecture in 1997 (McGill University), and the Keynote Lecture at the 1999 Decade of the Brain meeting before the NIH and the Library of Congress,  as well as the Rabindranath Tagore lecture at the Centre for Philosophy and Foundations of Science in New Delhi.  In 2003 he gave the annual BBC Reith Lectures.  In 2007 he gave a public lecture that was part of a series sponsored by the Templeton Foundation at the Royal Society in London.  He gave the 2010 IAS Distinguished Lecture at the University of Bristol‘s Institute of Advanced Studies dedicated to the memory of his longtime friend and collaborator, Richard Gregory. In October 2011, Ramachandran delivered a lecture titled “The Neurology of Human Nature” at the 47th Nobel Conference at Gustavus Adolphus College in Saint Peter, Minnesota. In 2012, he gave the Gifford Lectures (May 28, 2012 – May 30, 2012) at the University of Glasgow.

Testimony as an expert witness

Ramachandran has served as an expert witness on the delusions associated with pseudocyesis (false pregnancy). At the 2007 trial of Lisa M. Montgomery he testified that Montgomery suffered from severe pseudocyesis disorder and that she was unable to appreciate the nature and quality of her acts.

Minotaurasaurus ramachandrani

An interest in paleontology led him to purchase a fossil dinosaur skull from the Gobi desert, which was named after him as Minotaurasaurus ramachandrani in 2009.A controversy has surfaced around the provenance of this skull. Some paleontologists claim that this fossil was removed from the Gobi desert without the permission of the Chinese government and sold without proper documentation. V.S. Ramachandran, who purchased the fossil in Tucson, Arizona, says that he would be happy to repatriate the fossil to the appropriate nation, if someone shows him “evidence it was exported without permit”. For now, the specimen rests at the Victor Valley Museum, an hour’s drive east of Los Angeles.

 

VS Ramachandran on your mind

Posted on February 9, 2012

This week’s TED talk comes from VS Ramachandran, who is Director of the Center for Brain and Cognition and Distinguished Professor with the Psychology Department and Neurosciences Program at UC San Diego. I first became aware of Dr. Ramachandran, as I’m sure many others did, when I read his fascinating book Phantoms in the Brain: Probing the Mysteries of the Human Mind. He has written several other books as well and I am particularly interested in his most latest work, The Tell-Tale Brain: A Neuroscientist’s Quest for What Makes Us Human, Ramachandran is an MD, PhD who’s research is focused on using patients with neurological disorders to understand normal brain function. In this TED talk, he talks about three patients with different syndromes (Capgras delusion, phantom pain, synesthesia) and how understanding them has either led to therapy or a better understanding of mental connections. (I’m not a neurologist, but I would gather that calling synesthesia a disorder or disease would be a no-no, from the few people I know who have it, but that’s for others to debate).

I enjoyed the talk immensely. Ramachandran is a great speaker and his work is on a clearly fascinating subject manner. In addition, the way he goes about discovery is akin to solving a murder mystery and often involves cheap or non-modern equipment (which gives him a sort of MacGyver feel, I suppose). His path of discovery makes for good and informative story-telling.

My only beef was one statement he made early on in the talk when he called neurons “little wisps of protoplasm.” Not quite. The molecular and cellular biologist within me cringed at that description. Yes, there’s brilliant and beautiful complexity at the level of the brain that he studies, but neurons themselves are pretty darn complex too. This can only add to the story.

A biologist’s view of science & religion

Issues at the interface of science and religion

 

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