Even before the discovery of “mirror neurons” — brain cells activated when we observe the actions of others that enable empathy — Dr. V.S. Ramachandran was using real mirrors to change the brain and relieve pain.
In the 1990s, Dr. Ramachandran devised mirror therapy to help amputees suffering from phantom limb pain — an agonizing experience in which patients feel pain “in” their missing limbs. By placing a mirror to reflect the existing limb in a position that makes it look like the missing one, the brain’s distorted image of the phantom can be changed. When the amputee moves the existing limb into a comfortable position, the reflection in the mirror — the phantom limb — “moves” with it, and pain in that missing limb often disappears, sometimes forever. (More on Time.com: 5 Ways to Stop Stressing)
The treatment is now widely accepted — not just for phantom limb pain, but for chronic pain of other types — and works in 70% to 80% of appropriate cases.
Ramachandran, who is the director of the Center for Brain and Cognition at the University of California–San Diego, has made a career of studying quirky neurological problems and finding not only new treatments for them but also profound insights into the way the brain works. I talked to him about his new book, The Tell-Tale Brain: A Neuroscientist’s Quest for What Makes Us Human.
What did you think when you first heard about the discovery of mirror neurons in 1995?
I’m quoted all the time for a remark saying that [mirror neurons] will do for psychology what DNA did for biology. It was sort of a whimsical remark and wasn’t intended to be entirely serious but it got picked up by the press and caused a little skepticism, not just of my remark but about mirror neurons in general.
My prophecy is already starting to be fulfilled — not completely, but the discovery has had a huge impact and encouraged people to think along new lines. It did provide a new point of departure. There’s also a lot of hype, which is unfortunate because it tends to mask the true importance of mirror neurons. The fact that hype exists doesn’t prove that something is not important. (More on Time.com: Post–Super Bowl Heartbreak: Cardiac Death Risk May Rise for Losing Fans)
In your book, you write about how you can anesthetize someone’s arm, then give the sense that it is being touched, by touching someone else’s arm. Tell me about that.
For 200 years we’ve known about phantom limbs, and yet nobody asked a phantom limb patient to watch another patient being scratched or touched to see if they feel the touch in their own phantom limb. So, we said, “Look, here’s a direct demonstration of mirror neurons in a person who is neurologically normal but his arm has been removed.”
And, yes, you can find some semblance of this even if you just block a person’s arm with an anesthetic. They instantly start feeling touch on another person’s arm [placed in the same position].
What does this tell us about our ability to empathize?
It shows that we are constantly empathizing all the time. But you don’t dissolve into the other person, so you need some kind of complicated circuitry telling you, “Empathize by all means, but don’t dissolve into that person.” Part of that comes from the frontal lobes and part of it comes from your own skin, which is not being stimulated. [That lack of stimulation tells you that it’s someone else who is having the experience, not you.] It’s this triadic interaction between frontal inhibition, mirror-neuron activity and your skin that allows you to empathize and simultaneously preserve your own identity.
You might take from this that we’re not as alone in our own skin as we think we are.
Yes, I’ve called mirror neurons “Gandhi neurons” for that very reason.
Can you “unlearn” pain?
In the case of chronic pain, one of the main things we’ve shown is that vision can powerfully modulate pain in different contexts. There’s a kind of pain called complex regional pain syndrome. This is seen after a trivial injury to a finger or something — normally it heals, but sometimes something backfires. I call it learned pain. Every time you try to move the finger, you feel excruciating pain. Then, in a sequence of extraordinary changes, the skin becomes inflamed and warm, the finger gets swollen permanently, and the pain and swelling and inflammation spread to the hand and to the entire arm, and it gets paralyzed. It’s seen in stroke, in as many as 10% of stroke victims, with intense excruciating pain in the paralyzed arm. (More on Time.com: Healthland’s Guide to Life 2011)
[To unlearn the pain,] you look at the mirror and you touch and stroke the normal hand and you wiggle it; [in the reflection,] you see the other hand being touched and stroked and wiggling without any pain. So, therefore, what happens is you unlearn the learned pain.
Does it happen immediately or do you have to repeat this many times?
You do need to do it many times. But what is astonishing is that you see the change immediately. Sometimes the temperature of the skin drops as you’re doing it.
A lot of treatments for stroke don’t work, and one of the things that’s been adopted widely is the constraint therapy, in which you immobilize the other arm and forcibly use the paralyzed arm. The patients often hate it, doing it for hours and hours at a time, hours a day for weeks. Here we’re doing the opposite — it’s the exact opposite principle.
What explains apotemnophilia, a condition that causes people to want their limbs cut off?
One key idea in the book is that the brain abhors discrepancies. It is seeking consistency.
So we decided to look at it from a neurological standpoint. We were struck by the similarities between this disorder and one in which a patient denies ownership of a limb [somatoparaphrenia]. If you’ve got a right parietal stroke, often in the right superior parietal lobule, it can make you say, “This arm doesn’t belong to me.” What’s going on is that initially, information from the arm goes to the somatosensory cortex — that’s where you process the sensations. Then, it goes to the superior parietal lobule in the right hemisphere, where you construct body image — so when you shut your eyes and move your arms around, you have a vivid sense of being anchored in your own body. (More on Time.com: Misery Has More Company Than You Think, Especially on Facebook)
A right hemisphere stroke typically affects both the sensory regions of the brain and the area where the body image is constructed. So, in a sense, there’s no discrepancy coming in; the two parts of the brain are both signaling that there’s no arm. But the patient typically denies the arm because there’s no way for him to account for this except to say there is no arm.
People tend to come up with these absurd delusions that it belongs to their mother or to their father or whatever. Sometimes there’s a paranoid streak to it — they’ll say the arm is a communist and won’t listen to me, and things like that.
So, people deny the arm because they have no longer have a map for it in their brain?
That’s correct. Now with apotemnophilia, you’ll get a different reaction from patients. You’ll ask, “So this arm doesn’t belong to you, and that is why you want to have it removed?” They’ll say, “No, on the contrary, it belongs to me too much. It’s overpresent, it’s intrusive, and that’s why I want it removed. I know I’ll be happier if it’s gone.”
And that’s because, we reasoned, the sensory strip is normal, so the map is normal, but the body image center is missing an arm. There’s a whole scaffolding of your body in the superior parietal lobule, which is missing an arm representation. The sensory input comes in and it gets sent to the body image center but there’s nothing to receive it. That produces an acute sense of discrepancy and the brain is intolerant to this.
About a third of these patients get the arm amputated, and they become very happy. Invariably, they lose their depression. But this is a telling interaction between basic physiological processes, body image and high-level thought processes.
What might transgendered people have in common with those who feel that their limbs don’t belong to them or should be cut off?
They’re in a similar situation in that their body image map doesn’t have the [ordinary] representation of genitals. Normally, in sexual development, there are four factors: One is sexual identity — I’m a male or I’m a female. There’s sexual morphology or anatomy [whether your body is actually male or female]. There’s sexual orientation — what you’re attracted to. And then there’s sexual body image: when you close your eyes and imagine your body parts, what do you feel like?
Sexual body image is probably located in the superior parietal lobule. Ordinarily, these four things cohere. But if there’s a lack of coherence and you get a body image that’s different from [the anatomy], it produces an acute discrepancy.
So men feel that their penis doesn’t belong to them, and the women feel that they have a phantom organ?
That’s correct. A lot of female-to-male transsexuals report phantom penises.