In the century that has passed since Freud set out to establish a “physiological psychology”, most of the big questions he was trying to answer remain. What is the self? What is consciousness? What is actually going on when we think?
In recent years techniques for scanning the brain to detect electrical activity and blood flow have become very powerful, but there is still a huge gap between the actions of individual neurons and significant operations of the brain such as remembering, reasoning and making decisions, which must involve millions of neurons working in ways that are still a mystery.
But recently neuroscientists have discovered a fruitful new approach, looking not at single cells but at beliefs. We all have beliefs – assumptions about the state of ourselves and our surroundings that are essential to filling in gaps in the data our senses give us and formulating plans for everything we do. By their nature, beliefs can be wrong. And it is extreme cases of beliefs gone wrong that constitute much mental illness.
It turns out that there is a range of very rare and very odd syndromes to do with beliefs on which it is actually possible to perform experiments. And the results of these experiments are leading to highly novel theories about the workings of the mind.
In some of these syndromes, otherwise sane patients who happen to have a paralyzed limb will insist vehemently that it is not paralyzed. Others claim that their parents, friends, and even old pets are impostors. Others decide that they are dead and then, perversely, try to commit suicide. Others behave perfectly normally but lose the ability they acquired at a very early age to understand what a mirror is.
These phenomena have been known for a long time but tend to be dismissed by clinicians as anomalies. After all, how could hard science get to grips with these problems? Leading the field in devising ingenious answers to this question is Vilayanur Ramachandran, a medical doctor turned neuroscientist who heads the Brain and Perception Laboratory at the University of California San Diego.
Ramachandran first worked at Cambridge on visual perception. He then made his mark in neuroscience by showing how the brain reorganizes itself after an amputation. This led to further work on phantom limbs. Most people who lose an arm or leg feel mysteriously as if the limb is still there, often for many years. Often the phantom limb is painful. It can seem, for instance, as if the “fist” is clenched and digging the “fingernails” hard into the “palm”.
Ramachandran had the remarkable insight to bring vision into the equation. He devised a “virtual reality box” – just a cardboard box with a vertical mirror inside along the center line of the patient’s body. So for instance if the left arm is missing, the patient by moving the head slightly to one side can see the reflection of the right arm where the left one ought to be.
Ramachandran set this up for a patient suffering from the clenched “fist”, and told him to position the real arm exactly where the phantom was. He then told him to unclench both fists together. Amazingly after a few tries the phantom fist appeared to open and the pain went away! Apparently the sight of the “fist” opening was enough to convince the brain that it actually was opening.
This crossing-over between sight and touch was quite unexpected, and it shows that pain can be learnt and also unlearnt, which is of enormous significance for the clinical treatment of pain. Ramachandran puts it, “Pain is an illusion, like an optical illusion.”
He moved on to look at anosognosia, the condition of denying disease. This occurs in some cases when a stroke or accident causes damage to the right side of the brain, paralyzing part of the left side of the body. (Each side of the body is controlled by the opposite side of the brain.) The patient, who is otherwise entirely lucid, reports that the paralyzed limb is working quite normally, even though it obviously is not.
A patient with a paralyzed arm will confidently try to pick up a tray of glasses as if both hands were working and the glasses will crash to the floor. He will then come up with an elaborate excuse as to what happened, or say, “Clumsy me.” This goes on for two or three weeks after the trauma, at which point the patient admits the paralysis but often denies that he ever denied it.
There is a pressing clinical need to get patients to overcome their denial quickly because otherwise they will not do crucial exercises in the first weeks of rehabilitation. Ramachandran decided to experiment. He told a patient that as part of his neurological examination he was going to inject the arm in question with a local anaesthetic that would paralyze it for a few minutes. The patient agreed, and Ramachandran proceeded to inject a saline placebo. He then asked, “Mr C., can you move your left arm?”
“No,” the patient replied, “it doesn’t seem to want to do anything. It’s not working.”
Ramachandran then went on to inject the other (normal) arm from the same syringe. He asked the patient to try to move the arm, and, lo and behold, it moved. “How is this possible?” he asked. “I’ve just injected you with an anaesthetic!”
The patient replied, “I don’t know, Doctor. I guess it’s mind over matter.”
Of other research on anosognosia, probably the weirdest result of all came from Eduardo Bisiach and his colleagues at the University of Milan. They squirted cold water into a patient’s left ear, and for a few minutes she admitted her paralysis! When the effect of the cold water had gone, she went back to her denial. Irrigating the right ear had no such effect. “We have a truth serum!” is Ramachandran’s response.
“We’re showing that it is possible to perform experiments on people’s belief systems,” he says. The clinical significance is immediately apparent. Schizophrenia entails distorted beliefs about the world; anorexia, about one’s own body. Ramachandran has coined a new term for the work: experimental epistemology – “Just to annoy our philosopher colleagues!” he says.
Like anosognosics, patients with Capgras delusion are suffering from right-hemisphere brain damage. Again, they appear normal, except that they claim that their parents and others close to them are not the real people, just people who look like them.
It is clearly not a coincidence that it is nearly always the right hemisphere that is involved in these bizarre cases. Ramachandran has devised a novel theory to explain this. He thinks one of the functions of everyone’s left hemisphere is to construct belief systems about how the world works, turning an overwhelming mass of confused sensory information into something simple enough to understand. But sometimes these beliefs can get too far-fetched, and it is the job of the right hemisphere to act as a reality check, to override the left’s conjecture if it gets too divorced from the facts. If the right hemisphere is damaged, this does not happen, and an absurd belief can take over.
So as an example, Ramachandran considers the anosognosics. We all have pre-existing images of ourselves, of our bodies, our abilities, and so on. A paralyzing stroke or accident is a terrifying violation of that self. The brain tends to cling to the pre-existing body image and ignore the discrepancy between that image and current sensory input. In the case of minor discrepancy this is a good idea, but for a major discrepancy the right hemisphere must come into play. And if it is damaged, it cannot, so the patients insist they are not paralyzed.
The placebo injection appears to make the paralysis more acceptable to them, so they admit it, albeit temporarily. The cold water in the left ear, Ramachandran surmises, is in some way prodding the damaged right hemisphere into action for as long as the cold lasts.
In the case of the Capgras delusion, the connection between the patient’s face-recognizing mechanism and his emotion-recognizing mechanism appears to have been severed in the trauma. He sees a familiar face but feels no emotion, and so concludes, “This must be an impostor.” The right hemisphere is not there to say, “That’s ridiculous.”
Patients suffering from Cotard syndrome imagine that they are dead. Andy Young and Haydn Ellis at the Medical Research Council’s Applied Psychology Unit in Cambridge see this as the same thing as Capgras delusion – the patient finds the world baffling and according to his mood either concludes the problem is in other people or in himself. Young is skeptical of Ramachandran’s “reality checker” theory because he sees patients who alternate between the two states.
On the other hand Ramachandran is getting support from high technology at the Institute of Neurology in London. Ray Dolan and his colleagues set up some normal subjects with a Positron Emission Tomography system and Ramachandran’s virtual-reality mirror box. (Nature forthcoming?)
In the box the subject could see his left hand plus its reflection where he would expect to see his right hand. He was asked to move both hands up and down together. In the box this looked perfectly normal. The PET scan of the brain showed all the motor areas lighting up as expected. But he was then asked to move his hands in opposite directions – one going up while the other was going down. The vision in the box was then crazy – the subject could feel the right hand going one way but saw it going the other way. The scan showed the same as before, except for an area of the right parietal lobe lighting up. Ramachandran reacts with glee, “That’s the consistency checker!”
Dolan then turned the box around. Again the spot in the right brain lit up when the hands were going in opposite directions. It certainly seems that this part of the brain is reacting specifically to the paradox coming from the senses.
At Oxford, Peter Halligan and colleagues have been studying the opposite of anosognosia: instead of denying a disability the patients claim they have one when there is no organic disorder at all. This is commonly known as hysterical paralysis. Halligan’s patient, who had recently suffered a serious psychological trauma, could not move her left leg (again the left). Halligan strapped down the right leg so that it could not move and asked her to try to move each leg in turn. The PET scans of her brain showed the areas to do with intention to move lighting up as expected in both cases, but for the left leg, two new areas of the right brain lit up, presumably obstructing the intention.
Halligan suspects that an evolutionary-primitive protective mechanism is being activated. What is fascinating, he says, is that physiological activity can be seen apparently responsible for processes that had always been thought of as psychological. “We’re highlighting the unconscious,” he says.
Phantom pregnancy is another hysterical condition that is far less common than it used to be – presumably because there is now less social pressure on women to have babies. Remarkably, this mental condition brings about physical changes to the body: enlarged breasts, swollen abdomen and labor pains. “If a belief can cause fat to appear and disappear in a particular part of the body,” asks Ramachandran, “could it not make a tumor disappear?”
He is well aware that there are a great many cranks in the “mind over body” brigade, but he is determined that questions like this must be looked at. There are for instance several reports in the medical literature of warts being cured by hypnosis. Warts are caused by a papiloma virus. Cervical cancer is also a papiloma virus – the possibility is breathtaking. So Ramachandran is planning to study for instance whether it is possible to hypnotize away the warts on one side of the body but not the other, and whether the pathway from the brain to the warts is neural or via the immune system.
So where is all this taking us? It is striking that so many of the phenomena described have to do with the notion of the self: anosognosics have suffered an assault on the self, Cotard patients conclude their self is no more. So could this work actually be leading to answers to the big questions of psychology? Patricia Churchland, a philosopher at UCSD who has long been prominent in the debates about mind and body, doubts that it will be enough. “All of those questions are going to require work at many levels of organization of the brain,” she says. “We aren’t likely to be able to answer those questions without knowing in detail how individual neurons work, how the patterns of connectivity are set up and so forth.”
Ramachandran agrees, but cites Horace Barlow’s warning that most of the neurologists working now are like Martians trying to understand the testicles without knowing anything about sex.
What is certain is that the distinction between neurology and psychiatry is becoming blurred. As Peter Halligan puts it, “We are fast demystifying the twilight zone that separates studies of mind and body.” It must be the aim of neurological research to show that all psychological conditions are in fact physiological – whether this prospect pleases psychiatrists or the mass of humanity remains to be seen. Certainly the implications for social constructs such as responsibility, blame and the criminal justice system, says Patricia Churchland, are daunting. But this is the kind of dilemma science has faced ever since Pandora opened her box.

BOX

The Transitory Self
The Illusion of Decapitation

We tend to think of the self as permanent and durable, but another of Ramachandran’s experiments, inspired by William Lackner, shows it is transitory and continually being updated. You can do this yourself with two friends. Close your eyes, and stroke the tip of the nose of one of your friends. Then get the other to stroke your nose exactly in time with your stroking. A metronome helps. You begin to feel your head out there where your hand is!
Ramachandran and his colleague William Hirstein have a more elaborate demonstration of the same thing. Through a half-silvered mirror you can see your lips superimposed on the face of a dummy. As you speak, you see the dummy’s lips move in perfect synchrony with yours. You can feel as if your free will is controlling the dummy’s lips. Subjects are apt to say, “I feel like I’m there now.”
“It’s as if your self has deserted you and moved over to this other body, as if your mind were no longer loyal,” is how Ramachandran puts it.
He goes a step further and pinches the nose of the dummy, while measuring your galvanic skin response. The needle jumps, as if your real nose had been pinched. “Here is objective proof,” says Ramachandran, “that your self is identifying with the dummy.”