Robyn Williams: Further south in California is one of the great centres of research in America at San Diego and that's where Professor V. S. Ramachandran studies the brain and the people who have unusual ones. Rama, as he's called, has written about phantom limbs, given the Reith Lectures for the BBC and studied the psychological origins of art. Now he's on the track of the phantom penis.

V. S. Ramachandran: Yes, it's part of the whole nature-nurture debate, which is really a spurious debate because it's always a complex interaction between the two. One striking example of this we've seen recently is some work I've done talking to transsexuals; these are people who want sexual reassignment surgery. A typical remark from a transsexual male-to-female would be, 'I feel like a woman trapped in a male body, and this appendage, this penis, doesn't really belong to me and I want to get rid of it and I want to become a woman.' People always thought this was just psychological mumbo-jumbo but there is a significant number of people who experience this, and we started wondering about this and said: why? What's going on in their brain?

Now, it turns out that if 'normal people'...and I put it in quotes because it's important to emphasise that there's nothing wrong or abnormal about being a transsexual, it's part of the whole spectrum of human sexuality and sexual behaviour. But it is curious that most normal people who have carcinoma of the penis, which is not rare, and they have an amputation of the penis as a life saving measure, a majority of them, maybe about 80%, 85% of them, experience a phantom penis, including phantom erections. This is well known. Since this chap is saying his penis doesn't belong to him in the first place, what if his penis is amputated because he wants to become a woman, what happens then?

The answer is the majority of them don't experience a phantom penis. What's amazing is that your body image, which includes your genitals, is at least in part programmed by genes and your brain is hard-wired to incorporate the genitals as part of your body image. Even more amazing is the observation that women who undergo transgender sexual surgery who acquired an artificial penis, a majority of them since early childhood have experienced a phantom penis. This is absolutely extraordinary because it means that each of us has a brain-based body image which is detailed down to the fine anatomy, including your genitals.

If your brain body image does not match...normally your brain body image and your external morphology are synchronised in early development through hormones, through genetic mechanisms. If this gets uncoupled and they aren't in synchrony you end up with a body image that's morphologically male, so they experience a phantom penis. What's amazing is that all these years of culture being raised as a woman, as a girl, and even seeing that they don't have a penis does not correct this body image. This shows that even though your body image is extremely malleable, as we have shown with phantom limbs and mirrors and that sort of thing, it also turns out that there's a strong genetic contribution to your body image. This has, of course, great implications for understanding how your brain represents sexual behaviour and constructs body image.

Robyn Williams: How do you know that the information that you've been given is not unreliable but not wishful thinking? Because the women may say this and you might believe them but how do you know it's necessarily as profoundly genetic as you imply?

V. S. Ramachandran: We don't know for sure except for remarks such as when they were first given testosterone therapy (this is sometimes done prior to surgery) the phantom becomes much more vivid. They also said things like they have phantom erections, which men do even after carcinoma. But even more amazingly they'll say things like they get erections even with non-erotic situations, suddenly it becomes erect and this is very embarrassing. Now, for somebody to make up a story like that is quite unusual and you hear the same thing again and again in different women who have not talked to each other.

The other thing is they'll give you precise descriptions of its length, they'll say sometimes it's leaning to the left primarily, or they'll say its angle between the pubic bone and the penis is such-and-such. The precision of the descriptions often gives somebody who has experience with clinical neurology the idea that this is probably not confabulatory. Of course you can't be absolutely sure. And the other thing is some of them also after breasts are removed, which is often the case, they don't have phantom breasts, whereas when breasts are removed for carcinoma then the majority of women experience phantom breasts. So there's that observation as well which is consistent. So this suggests strongly that this is a hard-wired body image thing and not just a confabulation.

Robyn Williams: Of course it would make sense that we have such an image of our bodies because we run them without thinking, we know roughly where they should be and what they should be doing without looking around all the time, and we actually walk through rooms in the dark without falling over. So this is more or less the necessity of it, is it?

V. S. Ramachandran: That's true, but on the other hand one could equally argue why such a high degree of precision? After all, you can fashion aspects of your body image using visual input, so why do you need to hard-wire it? And that's a difficult to answer. Another striking example I've seen in India, and this has been described in the older literature, it's not our discovery, is that people with leprosy progressively lose their fingers until the arm becomes shorter and shorter, the forearm, but these people never experience a phantom hand.

The standard argument is that it's because they've gradually seen it shrink, so their body image is able to accommodate the changing appearance of the hand. But now if there's a little gangrene in the stump and you go and mess around with it, try to treat it, make it heal, what happens is the entire phantom gets resurrected. So it's as though the phantom hasn't really gone, the internal body image, it has somehow been inhibited temporarily, and when you go and mess around with it, it gets resurrected. So that's another example of how it's not just genetic or just environmental but a complex interaction between the two.

Robyn Williams: It's amazing. How are you following up this work so that you get a more global picture of what it means?

V. S. Ramachandran: We are following it up by...the usual tactic is to do brain imaging, which is what we did with the phantom limb experiments. For example, what happens when you put a mirror and you have a phantom and you animate the phantom using a mirror image and it starts moving, what happens in your brain? (?Hertefler43:34), who has been working on this in Finland, has done it, repeating our experiments with mirrors and showing that in many of them, about half of them, the phantom just disappears and the pain disappears, but now she's following this doing brain imaging to show what happens to your body image in the brain. So that will be the obvious next step.

But let me add here, when you think about body image it's hard not to think of you being a person anchored in a body, and this takes you to the question of consciousness and self-awareness, and this is of course a hot topic. Crick and Koch have talked about it, the Churchlands have talked about it, Damasio has talked about it, and every magazine you pick up there's a chapter on consciousness. I'll give you my take on it, for what it's worth. Self-awareness; I'm aware of red but I'm also aware of me, and I'm aware of me being aware of red. It's this somewhat solipsistic aspect of self that has remained completely mysterious and continues to remain mysterious. It's probably the greatest challenge to science. In fact, one could argue it's the most important problem of all; who am I? What is the self?

I think the answer comes from (?Ritselati's44:41) discovery of motor neurons. It turns out there are neurons in the front of your brain and the neuron will fire when you reach out and grab something, another neuron when you grab a peanut, another neurone when you remove your spectacles, another neuron when you put something in your mouth, another neuron when you push something or pull something, different neurons for different complex skilled actions. This has been known for 30 or 40 years, but what is amazing is that some of these neurons will fire when a monkey watches another monkey doing the same thing, or another human watches another person doing the same thing. So you call these neurons 'mirror neurons' which fire when somebody else is performing the same action. So it's as though the monkey or person is performing a virtual reality simulation, putting yourself in the other person's shoes and viewing the world from the person's vantage point. This is extremely important because you're constructing a theory of other minds, and to do that you use your mirror neurons. In other words, it's not merely to predict that person's actions but to predict their intentions, to infer what's going on their minds.

All I'm saying is what you're doing now...take the same mirror neurons which were evolved to generate a theory of other minds and to make predictions about their behaviour. That's what evolved first. Turn it inwards and...see, when you think about yourself, I don't think of self as one thing, it's several things like being anchored in your body, a sense of planning for the future, a sense of willing actions, doing things. So there are many components to will, but one of the things I notice when I introspect...introspection is not fashionable but I think it's a good thing to do...when you introspect you have a sense of yourself watching yourself from above; I'm doing things and I'm watching myself doing things. It's obvious that mirror neurons might be involved there because just as you're imagining the other person's point of view looking at a peanut, you can imagine the other person's point of view looking at yourself.

I think even things like reflecting on yourself, things like introspection may involve this very same neural system, and being able to turn inwards to create representations of what's going on in your own brain, creating what's called introspection or your sense of self. I think this is why we use words like 'I reflect', or we use words like 'I'm self-conscious'. What you really mean is not that I'm self-conscious, you mean I'm conscious of somebody else being conscious of me, and that's why you get embarrassed. So why do you say self-conscious? So all of these indirect bits of evidence and evidence from clinical neurology, work we have done, suggest strongly that in fact self-awareness may depend on other awareness, or other awareness evolved first and then that same algorithm was applied to yourself.

So how do you test this? Well, we're looking at patients, for example, with denial, anosognosia, and these patients deny that their left arm is paralysed and this is because there's additional damage to parts of the parietal lobe concerned with body image. The extraordinary thing is that some of these patients will deny that another patient is paralysed, even though the other patient is paralysed. So you can see how mirror neurons dissolve the barrier between you and other people and I call them empathy neurons, the Dalai Lama neurons, okay? In fact there are mirror neurons in the anterior singular which will fire when I poke you with a needle, so people used to think of these as pain neurons. Amazingly some of them will fire if you poke somebody else with a needle. So that's why I call them empathy neurons.

And mind you, one isn't just being metaphorical here; that neuron simply doesn't know the difference between you being poked and another human being poked. So I think that mirror neurons are going to be very important in thinking about some of these very enigmatic aspects of the self. I don't think anybody has talked about its relevance to self-awareness and introspection, and I think that's where some new experiments can be done to explore this.

Robyn Williams: Very interesting. I have to ask a naïve question about mirrors, not mirror neurons but mirrors. There are various animals who recognise themselves in the mirror, apes being an example and of course elephants more recently surprisingly seem to be able to do this. Is that connected at all, this recognition of yourself in the mirror with the mirror neuron that you describe?

V. S. Ramachandran: I don't know but I don't think so because I think what's going on in a mirror...let me tell you about a patient again because it's what I do for a living. We had a patient who had some kind of dementia but her IQ was maybe around 90, she was not mentally retarded or anything. This woman had a problem and when she looks at a mirror she says, 'That woman is not me. Who is that strange woman in the mirror? She's following me. She's haunting me.' She'll even say when somebody else, her husband is standing next to her, 'That's my husband's brother, it's not my husband.' She looks in the mirror and says, 'That's not me.'

But now you do the famous Gallop test. What you do is when she was asleep I put a splotch of ink on her forehead. She gets up, looks in the mirror, immediately wipes off the splotch of ink. And then she says, 'Who is that woman?' So this means that the Gallop test is not really an adequate test for inferring that merely identifying the person in the mirror as you implies any type of self-awareness. I think it's not an adequate test. So the implication of the Gallop test is a bit dubious. I think it's a very ingenious experiment, but to say just from the Gallop test that somebody has introspection, some creature has awareness of self, is a little bit premature I think.

Robyn Williams: In fact the experiment was involving a gorilla and various other animals who had, indeed, that mark on the forehead which they then studiously wiped off because they recognised that it shouldn't be there.

V. S. Ramachandran: Yes, this implies that they have some sense of parts of their body and they can reflexly remove something, just as if there's a fly or something they might reflexly remove that, and with frequent practice with a mirror they somehow infer that this is their own body. To that extent they have self-awareness but not in the sense that humans do of introspective self-awareness, of me being a person anchored in the body, having a sense of future and past, being able to unite diverse sensory experiences and memories and all of that, which is what you and I mean by being aware of self. That kind of self-awareness is not proved by the mirror test.

Robyn Williams: Professor V. S. Ramachandran at the University of California San Diego. He gave the Reith Lectures three years ago.