Hey, am I there?

Disclaimer : This post is a translation of a note by Professor Vileayanur Ramachandran , about the phenomenon of out-of-body experience and various anomalies associated with the perception of "yourself." Although the original was published in May 2010, the article contains a number of interesting examples from clinical practice and, in general, seemed quite interesting, and therefore wanted to share it.

If there is something in which you can be sure about yourself, it’s that your “I” is tied to your own body and belongs only to you. The person that you feel is here and now, and nowhere else.

But even the very basics of your existence can be questioned under certain circumstances. Your feeling of being in your own body, as it turned out, is just a subtle inner structure, like any other experience, and just as much is subject to illusions and distortions. Even your own “owning” feeling is fundamentally no different, in terms of evolution and neuroscience, from owning your car (if you are Californian) or your gun (if you're Republican).

Strange as it may sound, what you think about as yourself is not the monolithic entity that you / it considers itself to be. In fact, one can pharmacologically control the sense of possession of the body with ketamine, which reliably generates out-of-body experience in normal people. Ketamine patients report a feeling of hanging over their own body and watching it. If someone decides to prick them, they can say, "My body, down there, feels pain, but I myself don't feel it." Since in such patients, the “I” ceases to be associated with the body in which it lives, they do not experience any agony or negative emotions (for this reason, ketamine is sometimes used as an anesthetic).

Your sense of having a body and feeling like a separate entity seems to come from those brain cells that are known as mirror neurons. Located in the premotor cortex, they interact with your prefrontal cortex, the part of the brain that makes plans and makes decisions. Usually, when you move your hand, say, to take a pen (a movement that accompanies the feeling of having free will), certain motor-command neurons of the motor cortex are excited. It's amazing how Giacomo Rizzolatti from the University of Parma in Italy, along with his colleagues Marco Jacoboni and Vittorio Gallese, demonstrated that some of these neurons are also excited when you just watch someone else perform the same actions.

Mirror neurons allow you to put yourself in the shoes of another person. In fact, your brain says: "The same neurons are excited when I move my arm, so I know what it feels and intends to do." In addition, neurons, which we can simply call “tangential mirror neurons,” are energized when you are touched or you see someone else being touched. The fact that people have such abilities was intuitively guessed by Charles Darwin, who wrote that when you watch how a javelin thrower is going to make a throw, the muscles of your legs can twitch unconsciously. Or when a child observes a mother who uses scissors, he unknowingly squeezes and unclenches his jaws. In this phenomenon, we see evolutionary prerequisites for the ability to imitate and repeat - the basis of the cultural transfer of knowledge.

At the same time, as you grow up, you cease to imitate uncontrollably the actions of those you look at; your self does not feel like a doll that is ruled by others. You retain your feelings of free will and action (although patients with Tourette syndrome sometimes exhibit unconscious imitation).

The tendency to uncontrollably imitate the people with whom you are, usually stops with your prefrontal cortex (evolutionarily, the most developed part of the brain that is expressed in humans). Not so long ago, we assumed that the interaction between mirror neurons and the response from the prefrontal cortex is what gives us a peculiar dual character - the simultaneous maintenance of individuality and interrelation with others.

Disorders in this system lead to out-of-body experience, which may explain the mechanism of action of ketamine. Under his influence, you “empathize” with your body, in the same way as you empathize with other people, and at the same time, you are able to separate yourself from it, just as you separate yourself from others.

Tricks with the disappearance of yourself

To reproduce this separation, you do not have to take ketamine. If you have enough money, you can do it with exciting virtual reality technology. For the rest of us there are a few simple optical tricks.

For example, try looking at a Halloween mask through a shiny glass panel, so that you can see the reflection of your own face superimposed on the mask. You can optically combine these two "faces", getting an unusual hybrid creature. Now try to take strange facial expressions, and you will get the feeling that the creature is absolutely synchronous imitating your antics. This experience should give you an instant feeling of decapitation — a hint of how you feel from taking ketamine.

The illusion can be enhanced if you place two glass panels at right angles. Move your head until the reflection of the center of your nose is exactly on the corner of the two panels (superimposed on the mask behind them). Now, if you blink with your right eye - the reflection will also blink with your right eye (double reflection - cancels the distortion of the usual mirror reflection from left to right). The result will be an even stronger illusion that you are “infused” in a mask.

If you go even further - which includes a combination of proper lighting, makeup, mannequins and the effect of a mirrored room, which is created when you stand between two opposite mirrors of human height, creating an infinite number of optical clones of yourself, you start to feel the same effects that gives ketamine. In the mid-90s, we showed (along with William Hirstein and Erik Altshuler from the University of California, San Diego) that hitting a mask under similar conditions leads to instant fright. We measured the subjects' fear by objectively tracking the changes in resistance on their skin, which corresponds to how much they sweated. When I threatened one of the old masks that the subjects looked at (without using optics, which helps you identify with the mask), there was no fright. It is the feeling of connecting with the “other head” that leads to this.

Later, scientists used video cameras to create similar illusions of separation from the body, in which people felt that they were projecting their body to themselves outside. Such a creepy experience is similar to the one that can arise, say, from damage to the right parietal lobe due to a stroke. This is the area of ​​the brain that is apparently partly responsible for creating the image of our body, the feeling that we “inhabit” our own form.

Patients with injuries to the right parietal lobe sometimes feel that they see themselves outside (as is the case with ketamine), or experience a double sensation. A few years ago, we saw a patient with a brain tumor in the right fronto-parietal lobe, who was mentally healthy, except for the fact that he felt a phantom twin attached to the left side of his body, repeating his every movement. If a patient was touched, he also felt that his twin was touched a few seconds later. Stimulation of the vestibular canals in the patient’s inner ear has led to sensations that he is spinning around, and his phantom is compressed and shifted (the vestibular apparatus, which provides balance and orientation in space, is connected to the right parietal lobe).

The great English neurologist, MacDonald Critchley described many other patients who, depending on the region of the parietal lobe, felt like giants or pygmies, felt parts of their own body as distorted or swollen. Cases of patients who felt that their own hand did not belong to them and claimed that it was the hand of their mother, or even hated a separate limb, declaring, for example: “my hand is a communist”. We believe that the feeling of owning even external objects (wedding rings, tennis rackets), which is so common in our species (Gandhi, in this case, a remarkable exception), may be a by-product of the neural systems that originally developed for the possession of the body.

Mirror medicine

Earlier, we noted that the reason why you don’t imitate other people or don’t feel touch to another person while watching him is that your prefrontal cortex inhibits the work of mirror neurons. The second reason may be that when you see another person being touched, despite the fact that your mirror neurons are active, your skin receptors tell the brain that there is no touch to them, and this zero signal prevents you from activity of the mirror neurons reached the threshold of conscious experience.

But guess what happens if someone paralyzes your arm using an anesthetic? Surprisingly, we found (together with a UCSD graduate, Laura Case) that the patient, in this case, literally feels the touch in his immobilized hand, if he just sees how the other person is being touched. Or if the other person passes the ice cube, the patient feels cold in his own hand! Those. when you turn off signals from touching a healthy hand, the patient does not just “empathize” with others - he literally feels what they touch. The same thing happens in patients with phantom limbs. Observing how another person’s hand is massaged seems to ease pain in patients with an amputated hand.

It is clinically known that a visual response using mirror reflection can help alleviate phantom pains and paralysis after a stroke, possibly due to mirror neurons. We are currently exploring whether the illusion of separation from the body, created with the help of mirrors, can be used to reproduce the effect of ketamine and treat chronic pain syndromes, allowing the patient to separate from his own body and the pain that “it” is experiencing.

Surprisingly, even real pain in a real hand can be cured through an optical response. In particular, there is such a severe disorder as Syudec Syndrome, in which a tiny injury leads to constant excruciating pain, swelling and "paralysis" of the arm - a condition we called "learned pain and paralysis." In 1995, at a lecture held at the meeting of the Neuroscience Society in San Diego, we suggested using mirrors to treat this disease, and since then, several large-scale clinical trials have confirmed their effectiveness. Even the edema subsides, and this is a wonderful example of the interaction of mind and body.

The most bizarre distortion associated with body image is that absolutely healthy people want their hand or foot to be amputated. Together with UCSD colleagues, David Bragg and Paul McGeoc, we found that touching the skin of an affected limb leads to an abnormal sweating reaction that is not present when touching a healthy limb. Further, our study of brain scans showed that the affected limb is incompletely represented in the right parietal lobe (responsible for the body image), although the areas associated with touches located in the somatosensory cortex remained normal. This discrepancy between the exact sensory flow of signals from the hand and the incomplete representation of the hand in the brain creates a remarkable aversion to the limb [see

Thus, studying people with brain abnormalities or manipulating the sensory perception of healthy people using mirrors and other optical tricks can provide the key to understanding how the right parietal lobe of the brain creates an image of our body that exists in time and space.

Such observations have important implications, both theoretical and clinical. They suggest that what we call the sensation of touch, pain, sensation of the body, or even ourselves, is the result of the dynamic interaction of signals from three sources: sensory signals from the skin, muscles, and intestines; inhibitory signals from the prefrontal cortex; and the activity of mirror neurons that react to behavior that originates from neurons in other people's brains! From this unstable mosaic of brain activity, there arises your sense of the “I” embodied in the body, separated from others and possessing everything that you are.