Vilayanur Ramachandran - The Emerging Mind - The Reith Lectures 2003

Now I'll turn to another disorder which is also caused by damage to the right parietal and that is even more extraordinary. It's called denial or anosognosia . Remember most of these patients with right parietal damage also have some damage to the internal capsule so they are completely paralyzed on the left side of the body. It's what you mean by a stroke, this complete paralysis of the left side of the body, and most of them complain about this as indeed they should. They say when am I going to get better, my arm doesn't work. But a subset of them, a small percentage of them will vehemently deny that their left arm is paralyzed, and these are patients who don't have any neglect. They'll say doctor, it's moving fine. Why does this happen?

It's not clear but it is only seen when the right parietal is damaged, rarely seen when the left parietal is damaged and that gives out a clue. It tells you that the denial syndrome has something to do with hemispheric specialization. The manner in which the two cerebral hemispheres deal with the external world, especially the manner in which they deal with discrepancies in sensory input and discrepancies in beliefs. Specifically I would like to suggest when confronted with a discrepancy, the left hemisphere's coping style is to smooth over the discrepancy, pretend it doesn't exist and forge ahead. The right hemisphere's coping style is the exact opposite. It's highly sensitive to discrepancies so I call it the anomaly detector.

Now imagine a patient with a right hemisphere stroke left side paralyzed. The patient is sending a command to move the arm, he is getting a visual signal saying it is not moving so there is a discrepancy. His right hemisphere is damaged, his left hemisphere goes about its job of denial and confabulation smoothing over the discrepancy and saying, all is fine, don't worry. On the other hand, if the left hemisphere is damaged and the right side is paralyzed the right hemisphere is functioning fine, notices the discrepancy between the motor command and the lack of visual feedback and says, my god you are paralyzed. This was an outlandish idea but it's now been tested with brain imaging experiments and shown to be essentially correct.

Now this syndrome is quite bizarre - a person denying that he or she is paralyzed - but what we found about seven or eight years ago something even more amazing. Some of these patients will deny that another patient is paralyzed so the patient is sitting here. We saw the patient, another patient sitting in a wheelchair - I'll call him patient B - and I've told patient B move your arm. Patient B of course is paralyzed, doesn't move. And then I ask my patient - is that patient moving his arm? And the patient says yes of course he is moving his arm. He is engaging in denial of other people's disabilities.

Now at first this didn't make any sense to me then I came across some studies by Giaccomo Rizzollati, experiments done on monkeys. If you record from parts of the frontal lobes which are concerned with motor commands you find there are cells which fire when the monkey performs certain specific movements, like one cell will fire when the monkey reaches out and grabs a peanut, another cell will fire when the monkey pulls something, yet another cell when the monkey pushes something. That's well known. These are motor command neurons . But Rizzollati found that some of these neurons will also fire when the monkey watches another monkey performing the same action, so you find a peanut-grabbing neuron which fires when the monkey grabs a peanut. When the monkey watches another monkey grab a peanut, it fires. It's quite extraordinary because the visual image of somebody else grabbing the peanut is utterly different so you have to do this internal mental transformation to do that computation and for that neuron to fire and Rizzollati calls these mirror neurons. Another name for them is monkey-see monkey-do neurons and these neurons I think are the ones that are damaged in these patients.

Because think about what's involved in your judging somebody else's movements. Maybe you need to do a virtual reality internal simulation of what that person is doing, and that may involve the activity of these very same neurons, these mirror neurons. So these mirror neurons, instead of being some kind of curiosity, hold important implications for understanding many aspects of human nature like how do you read somebody else's movements, their intentions, their actions. Many aspects of what you called a theory of other minds, a sophisticated theory of other people's behaviour. We think it is this system of neurons that is damaged in these patients. The patient can therefore no longer construct an internal model of somebody else's actions.

I also want to argue that these neurons may have played an important role in human evolution and I am going to talk about this at length in my Oxford lecture on the emergence of language and abstract thinking, because think about it. One of the hallmarks of our species is what we call culture. And culture depends crucially on imitation of your parents, of your teachers and the imitation of complex skills may require the participation of mirror neurons. So what I'm arguing is somewhere around 50,000 years ago maybe the mirror neurons system became sufficiently sophisticated that there was an explosive evolution of this ability to mime complex actions, in turn leading to cultural transmission of information which is what characterises us humans.

Now let me conclude by emphasising once again that although the studies on patients are intriguing in themselves, our real agenda here is to understand in terms of brain function, us normal humans, how our brains work, the whole spectrum of abilities that we call human nature, whether it is body image or culture or language or abstract thinking and I hope to convince you that such a deeper understanding of the brain will have a profound impact not just on the sciences but on the humanities as well. Lofty questions about the mind are fascinating to ask, philosophers have been asking them for three millennia both in India where I am from and here in the West - but it is only in the brain that we can eventually hope to find the answers.

Thank you very much.

In this lecture - which is the most speculative one in the series of five - I'd like to take up one of the most ancient questions in philosophy, psychology and anthropology, namely what is art? When Picasso said: "Art is the lie that reveals the truth" what exactly did he mean?

As we saw in my previous lectures neuroscientists have made some headway in understanding the neural basis of psychological phenomena like body image, how you construct your body image, or visual perception. But can the same be said of art - given that art obviously originates in the brain?

In particular what I'd like to do is raise the question: "Are there such things as artistic universals?"

Now let me add a note of caution before I begin. When I speak of artistic universals I am not denying the enormous role played by culture. Obviously culture plays a tremendous role, otherwise you wouldn't have different artistic styles - but it doesn't follow that art is completely idiosyncratic and arbitrary either or that there are no universal laws.

Let me put it somewhat differently. Let's assume that 90% of the variance you see in art is driven by cultural diversity or - more cynically - by just the auctioneer's hammer, and only 10% by universal laws that are common to all brains. The culturally driven 90% is what most people already study - it's called art history. As a scientist what I am interested in is the 10% that is universal - not in the endless variations imposed by cultures. The advantage that I and other scientists have today is that unlike we can now test our conjectures by directly studying the brain empirically. There's even a new name for this discipline. My colleague Semir Zeki calls it Neuro-aesthetics - just to annoy the philosophers.