DENVER—“The reason we get into neurology in the first place is because we’re all interested in the mind, in what makes us tick, in what human nature is,” according to Vilayanur S. Ramachandran, MD, PhD. “Somewhere along the line we sort of lose track of this, and so what I’d like to do here is to revive interest in behavioral neurology, which today goes by the name of cognitive neuroscience,” he said at the 54th Annual Meeting of the American Academy of Neurology.

Dr. Ramachandran described one of the goals of cognitive neuroscience as developing conceptual links between brain anatomy, neurophysiology, and phenomenal experience. Using synesthesia, Dr. Ramachandran, who is Director of the Center for Brain and Cognition and Professor of Neuroscience and Psychology at the University of California, San Diego, illustrated how the study of certain neurologic syndromes can illuminate fundamental principles of the organization of the normal human mind.

SYNESTHESIA—THE PHANTOM MENACE?

“Synesthesia has lingered in the field as a curiosity,” he said. “Very few experiments have been done to investigate what synesthesia really is or what causes this phenomenon, although there have been three or four common explanations in the older literature.”

One explanation is that synesthetes are “crazy.” The second involves the use of drugs such as marijuana or LSD. “There’s some truth to this, but what about these people who don’t take LSD [and] have synesthesia all the time? How do you explain that?” Dr. Ramachandran wondered.

The third explanation is that synesthetes “played with numerical magnets when they were children. Five was red, six was blue, seven was purple, and it just stuck in their minds. This never made much sense to me. If there’s a relationship between playing with magnets and childhood memories and synesthesia, why don’t we all have synesthesia? Why does synesthesia only run in certain families?”

The last explanation is that synesthesia is a form of metaphor. “C-sharp is red just like a certain cheese is described as tasting ‘sharp,”’ Dr. Ramachandran explained. “The problem with this explanation is that you can’t use one mystery in science to explain another mystery. Saying that synesthesia is just metaphor doesn’t explain anything because we have no idea how metaphors are represented in the brain,” he said.

“What I’m going to do is turn the problem upside down on its head,” he proposed. “First we will show there is a neural basis [for synesthesia], which we have discovered. That in turn gives you an experimental foothold for understanding more enigmatic aspects of the mind, like what is a metaphor, what is language, poetry, so on and so forth. I’m going to try to bridge those gaps as we go along.”

THE MATRIX—PROVING SYNESTHESIA

“We did what I think is a decisive experiment,” Dr. Ramachandran said. “First of all, we determined that one out of 200 college people is synesthetic. We found two synesthetes who saw numbers as colors, and then we created a random matrix of fives. Scattered among the fives are some twos. They’re very hard to see. A normal person takes a second or two to find the twos and longer to realize they’re arranged in a shape. But when you show this matrix to a synesthete, he says, ‘Oh, I see a red triangle’—instantly. This shows that he’s literally seeing those twos as red, the fives as green, and therefore, he’s not making this up at random—if he were faking it, how come he is actually much better at this task than normals? This is a diagnostic test—a very sensitive marker for synesthesia. The results show that synesthetes are not crazy, it’s not a metaphor, nor is it just a memory association. This is the first experiment since the time of Francis Galton 100 years ago to show clearly that synesthesia is an authentic sensory phenomenon,” Dr. Ramachandran averred.

HYPERCONNECTING TO THE CAUSE

“We were struck by the fact that if you look at the fusiform gyrus, the color area of the brain is right next to the area that deals with visual graphics and numbers, almost touching it,” Dr. Ramachandran said. He proposed that some people have a gene mutation that causes either disinhibition or defective pruning of the connections between adjacent brain modules. “If there’s a gene mutation which causes defective pruning, and if it’s selectively expressed in the fusiform gyrus, where the number and color areas lie, you get cross-wiring between these areas causing number to color synesthesia.

“Later we stumbled on some synesthetes for whom even the days of the week and the months of the year had colors,” he added. “So we asked ourselves, what does a number have in common with the days of the week or the months in a calendar? The answer is, they’re all sequences. So my conjecture is maybe in these ‘higher’ synesthetes it’s the abstract concept of numerical sequence that gets linked to colors. Perhaps in these people the same gene is expressed in the vicinity of the angular gyrus where the abstract idea of numerical sequence is represented, and close to it is also another color area that’s further downstream from the color area in the fusiform. If the gene is expressed in the fusiform, you get a lower synesthete driven by the visual features of the grapheme; if it’s expressed higher up, near the angular gyrus, you get a higher synesthete in whom the color is evoked by the concept.”

Lastly, if the gene is expressed continuously everywhere there is extensive hyperconnectivity throughout the brain. “This explains, I think, why synesthesia is so much more common in artists, poets, and novelists. What do artists, poets, and novelists have in common? They use metaphor, analogy. They can take seemingly unrelated ideas and link them. For example, ‘It is the east, and Juliet is the sun.’ Now when Shakespeare says that, do you say ‘Juliet is the sun … does that mean she’s a glowing ball of fire?’ Of course not. You say, ‘She’s warm like the sun, radiant like the sun, nurturing like the sun.’ All the links are formed in your brain.

“Now, what I’m arguing is that these people have more cross-wired brains, so they can more easily relate seemingly unrelated concepts,” Dr. Ramachandran explained. “This seems quite outlandish an idea, but think about the fact that even concepts are laid out in anatomical regions, in brain maps. Once you accept that, the more extensive cross-wiring would explain the higher incidence of synesthesia in novelists, poets, and artists, if the gene is expressed more diffusely.”

THE ORIGIN OF SPEAK-EASE

“How did language evolve?” Dr. Ramachandran asked. Divine intervention, as posited by Alfred Wallace, “may be true, or it may not be true,” but it is scientifically unverifiable, and hence of little use, he observed. A second theory, by Noam Chomsky, postulated that “if you pack 100 billion nerve cells into this tiny space, the human skull, maybe there are new physical laws that emerge, and that’s how language arose. Now, this comes perilously close to Wallace,” Dr. Ramachandran noted. “Chomsky doesn’t say divine intervention, he says a sort of miracle occurred; that doesn’t really explain anything.”

Stephen J. Gould, in a third theory, said language evolved as a specific implementation of a more general ability called thinking. “Once we developed thinking, we employed that for communication, and that’s what we call language. Accordingly, language is an exaptation of thought. There may be a grain of truth, but overall I’m unhappy with it because it only postpones the problem. If you say language evolved from thinking, you have to explain how thinking evolved,” Dr. Ramachandran said, “and that’s an even bigger mystery.”

A fourth theory, by Steve Pinker, “says language is an instinct. It evolved through conventional natural selection, through a step-by-step hill-climbing algorithm shaped entirely by natural selection as a specific adaptation for the sole purpose of communication, but since you don’t know what the intermediate steps are, it seems utterly mysterious. The problem with this explanation is, even if it’s true, it doesn’t tell you enough. It doesn’t tell you what the actual critical steps were that led to the emergence of language.

“So—all of these theories are either wrong or inadequate, and I’d like to replace them with what I call the ‘synthetic bootstrapping theory of language’—the notion that language evolved as a result of fortuitous synergistic interactions between mechanisms—called exaptations—that evolved originally for other, completely unrelated functions. It’s a striking illustration of the principle that evolution often involves the opportunistic co-opting of preexisting mechanisms.”

In simple terms, Dr. Ramachandran’s theory states that synesthesia gave rise to language. “The first words our ancestors evolved may not have been arbitrary—there’s a non-arbitrary correspondence between visual object shape and sound ‘shape’ as represented in the superior temporal gyrus,” he explained. “The evidence for this is if you take two completely random nonsense shapes, one resembling an ink blot with undulating contours, and one resembling a shattered piece of glass with sharp corners, and ask 100 people, ‘Which one of these represents the nonsense word Bouba and which represents the nonsense word Kiki?,’ 99% of them pick the amoeboid as Bouba and the jagged shape as Kiki. Presumably, this is because the jagged edges synesthetically mimic the jagged sound of ‘ki-ki.’ This preexisting bias, however small, would have set the stage for a shared vocabulary—a lexicon.”

He added that “a sort of preexisting synesthesia also occurs in the brain between visual and hearing maps and the motor maps for motor speech sounds represented in and near the Broca’s area.” Additionally, there is a preexisting cross-activation entirely within the Penfield Motor Map between maps for mouth and hand movements that are right next to each other, he said. “That’s why when you cut with scissors you unconsciously clench and unclench your jaws. I call this ‘synkinesia’—an automatic tendency to move your lips to mimic your hands. Imagine our ancestral hominids developing a gestural communication system, and then your mouth and tongue mimic the movements of your hands, and then you get the first words by combining this vocal mimicry of gestures with guttural utterances and emotional cries emerging from the right hemisphere and the cingulate. Once you have these protowords and protolanguage in place, then from that you get the full-blown emergence of language,” he said.

“So what we have is a nonarbitrary translation: visual to auditory, auditory to mouth motor maps in the Broca’s area, and lastly from the hand motor map to the mouth motor map. These preexisting initial biases get progressively amplified by a sort of mutual bootstrapping or avalanche effect—a common occurrence in the evolution of systems,” Dr. Ramachandran explained.

“Notice what we have here,” he added. “You started with a bizarre, spooky problem, an object of curiosity, an anomaly—synesthesia, people seeing colored numbers—and brought them to the laboratory. With a large enough family, you can clone the gene(s) involved and then go from gene to specific brain anatomy to detailed psychophysics—such as the segregation and pop-out experiment with the matrix—and all the way to the emergence of metaphor, language, and abstract thought.”

MORE MATTER, LESS ART?

“Okay, so explain art,” Dr. Ramachandran challenged himself. “The question is, are there artistic universals, just like there are linguistic universals? There is a great diversity of styles in art, but could it be that despite this staggering diversity, there are some common principles, some universal laws? And then, of course, there’s the corollary: how does the brain respond to art?

“I became interested in this when I looked at Indian art,” Dr. Ramachandran said. “Until about five years ago, I had no interest in art at all, but then I started looking at sculptures in Indian temples when I was there on sabbatical. I would see the sculptures of the goddess Parvathi from the 10th century, and this was supposed to be the epitome of everything feminine—of sexuality, sensuality, grace, dignity, and poise—yet the English Victorians took a look at this and they said, ‘It’s hideous! It does not look like a real woman.’ Of course, they were making this criticism because they were unconsciously comparing Indian art with ideals of Western representational art, especially Renaissance and classical Greek art, and you all know that art is not about representation, it’s not about realism. On the contrary, art is about exaggeration, hyperbole, and deliberate distortion of the image to produce pleasing effects in the mind.

“Now, the great irony is, you come to the 20th century and look at Picasso’s example of a woman. She’s got two eyes on one side of her face, like a flounder, a cleft palate, a club foot, and everything else, and the Western art critics say, ‘My God, what a work of genius,’ because he has liberated us from Realism and made us realize that art is not about realism, it’s about distortion, hyperbole, exaggeration.”

Obviously, you can’t randomly distort the image and call it art, Dr. Ramachandran observed. “There are specific types of distortion. I came across a word for this, ‘Rasa,’ in ancient Sanskrit art manuals, which means ‘capturing the very spirit of something, the soul of something in order to evoke a specific mood or sentiment or emotion in the viewer’s mind.’ So the idea of art is to change the image in some way to more optimally titillate these 30 visual areas of the brain and excite visual emotions.”

Dr. Ramachandran proceeded to present the example of a seagull chick, which begs for food by pecking at a red spot on its mother’s beak. “Niko Tinbergen found you can wave a disembodied beak or even an oblong piece of cardboard with a red dot and the chick gets fooled and pecks at the dummy. Even more amazing, he found that if you show the chick a long thin stick with three red stripes near the end, the chick goes berserk. It pecks much more vigorously at this and prefers it to the real beak,” he said.

This “super-beak” more powerfully excites the “beak-detecting” neurons in the chick’s visual pathway “even though this abstract stimulus doesn’t even remotely resemble a real beak,” Dr. Ramachandran elaborated. “If the gulls had an art gallery, they would hang this long stick with three stripes on the wall, worship it, call it a Picasso, and pay millions of dollars for it, even though it doesn’t look like anything they know.” The human artist, Dr. Ramachandran continued, has “stumbled on forms that more powerfully activate visual and limbic centers in your brain than any realistic images. He has created the equivalent of the stick with the three stripes for the human brain.”

Dr. Ramachandran emphasized that these theories and observations are “no more than hesitant first steps toward a science of art—toward discovering artistic universals—the new science of ‘neuroaesthetics.’ ” To conclude, he returned to the questions about the human mind and consciousness he started with. “What is consciousness? What do you mean by falling in love? What is free will? What is ‘the self’? What is humor, music, art? How did language and abstract thinking and metaphor and poetry evolve in humans? When I was a medical student, these were things you pondered only if you didn’t want to get tenure. Now, given our wonderful imaging technology, if we ask the right questions, do the right experiments on the right patients, we can begin to answer these lofty questions about the mind which until now have remained in the domain of philosophers.”

—C. Justin Romano

Suggested Reading
Ramachandran VS, Hirstein W. “The perception of phantom limbs.” The DO Hebb Lecture. Brain. 1998;121:1603-1630.

Ramachandran VS, Hubbard EM. Psychophysical investigations into the neural basis of synaesthesia. Proc R Soc Lond B Biol Sci. 2001;268:979-983.

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