Understanding consciousness is the most difficult of all the tasks facing science. One can verify the validity of this statement by examining the career of Francis Crick, perhaps the most gifted and influential biologist of the second half of the 20th century. After World War II, when Crick began studying biology, it was believed that science faced two great unsolvable questions: what distinguishes the living from the inanimate and what is the biological nature of consciousness? At first, Crick turned to the simpler question of the difference between living matter and inanimate matter and began to study the nature of the gene. In 1953, after just two years of working together, he and Jim Watson helped science solve this mystery. As Watson later wrote in his book The Double Helix, “during lunch, Francis flew into the Eagle Pub to tell everyone who was sitting close enough to hear him that we had discovered the secret of life.” Over the next two decades, Crick helped science decipher the genetic code and figure out how RNA is synthesized on DNA and protein on RNA. In 1976, when he was sixty, Crick turned to the remaining scientific mystery — the biological nature of consciousness. He worked on it for the rest of his life in collaboration with Christoph Koch, a young specialist in computational neuroscience. Crick applied all his optimism and outstanding intelligence to the study of this issue. It is thanks to him that the scientific community, which had previously ignored this issue, is now focusing on the problem of consciousness. But in thirty years of continuous work, Crick has managed to make only little progress in studying the nature of consciousness. Moreover, some scientists and philosophers dealing with psychology still find consciousness incomprehensible and tend to believe that it will never be possible to explain it in biological terms. They doubt the fundamental possibility of knowing how a biological system, a biological machine, can feel something. They are even more doubtful about how she can reflect on herself. These issues are not new. For the first time in the history of Western thought, they were formulated by Hippocrates in the 5th century BC, and after him by Plato, the founder of the Athenian Academy. Hippocrates was the first physician to reject superstition and base his ideas on the data of clinical observations. He argued that all mental processes originate in the brain. Plato, who rejected observation and experimentation, believed that the only reason we can think about ourselves and our mortal body is because we have an immaterial and immortal soul. The idea of an immortal soul subsequently entered Christian philosophy and was developed by Thomas Aquinas in the 13th century. Thomas Aquinas and subsequent religious thinkers argued that the soul (the source of consciousness) is not only different from the body, but also has a divine origin. In the 17th century, Rene Descartes developed the concept that man has a dual nature: he has a body consisting of a material substance and an immaterial soul. The soul receives signals from the body and can influence its actions, but it itself consists of an immaterial substance inherent in all living organisms only to humans. Descartes’ ideas formed the basis for the idea that actions such as eating or walking, as well as sensory perception, needs, drives, and even simple forms of learning are mediated by the brain and are available for scientific research, but the psyche, that is, the soul, is sacred and as such should not and cannot be the subject of scientific analysis. It is noteworthy that these ideas of the 17th century were still in use in the 80s of the 20th century. Karl Popper, the great philosopher of science, and John Eccles, a neuroscientist and Nobel laureate, have been supporters of dualism all their lives. They agreed with Thomas Aquinas that the soul is immortal and independent of the brain. The British philosopher of science Gilbert Ryle called this concept of the soul “a ghost in a machine.” Today, most philosophers dealing with psychology agree: What we call consciousness is generated by the material brain, but not everyone agrees with the Cry that, in principle, a scientific approach is applicable to consciousness. Some, such as Colin McGinn, believe that consciousness cannot be studied at all, because the very structure of the brain imposes limitations on human cognitive abilities. According to McGinn, the human mind may simply not be able to solve some problems. Another extreme point of view is held by philosophers such as Daniel Dennett, who denies the very existence of this problem. Dennett proves, in much the same way that John Hewlings Jackson did a century earlier, that consciousness is not some kind of separate brain function, but a collection of the results of various computational processes occurring in higher-order cortical regions associated with the late stages of information processing. Finally, philosophers such as John Searle and Thomas Nagel take an intermediate position and believe that consciousness is a well-defined set of biological processes. These processes are available for study, but we have not yet made much progress in this direction, because they are very complex and amount to something more than the sum of their parts. Thus, consciousness is much more complex than any brain function that we have managed to figure out. Searle and Nagel attribute two features to consciousness as a state: unity and subjectivity. Unity as a property of consciousness reflects the fact that we perceive our sensations as a single whole. All of our sensory modalities merge into a single, coherent, conscious experience. Therefore, when I approach the rose bush in the botanical garden at Wave Hill Estate, I feel the subtle scent of flowers and at the same time perceive their red color and shape, and at the same time see this rose bush against the background of the Hudson River and the cliffs of the Palisades Range on the other side. The image I perceive will be complete not only at this moment, but also in two weeks, when I want to make a mental trip through time and restore it in my memory. Despite the fact that the senses of smell and sight are connected to different organs and that each of them uses its own separate pathways, these pathways converge in the brain so that I perceive a single, integral picture. There is a difficult problem with the unity of consciousness, but, in particular, perhaps it is solvable. This unity can sometimes fall apart. Patients who have surgically separated the two hemispheres of the brain have two consciousnesses, each of which perceives its own unified picture of the world. The second feature of consciousness, subjectivity, is associated with a more complex scientific problem. Each of us lives in a world of unique sensations that are more real to us than the sensations of others. We perceive our thoughts, moods and feelings directly, while we are able to evaluate the experience of other people only indirectly, with the help of sight or hearing. Therefore, we can ask the following question. Do your reaction to the blue color that you see, or the smell of jasmine that you feel, and the meaning that it all has for you, coincide with my reaction to the blue color that I see, and the smell of jasmine that I feel, and the meaning that it all has for me? The problem concerns not only perception as such. The question here is not whether we see very similar shades of the same blue. It is relatively easy to find out by recording the signals of individual nerve cells in everyone’s visual system. The brain reproduces our perception of an object, but it seems that the perceived object itself (for example, a blue color or a note up to the first octave on a piano) has corresponding physical properties, such as the wavelength of reflected light or the frequency of the sound produced. The question concerns the meaning of these colors and sounds for each of us. We have not yet figured out how the electrical activity of neurons provides the meaning that we attribute to a given color or sound. The fact that each person’s conscious experience is unique raises the question of whether it is possible to identify any objective features of consciousness that are common to all of us. If our feelings end up generating sensations that are entirely subjective, then, according to this argument, we cannot come to any general definition of consciousness based on personal experience. Nagel and Searle show the difficulty of explaining the subjective nature of consciousness in biological terms using the following example. Let’s imagine that in a certain part of the brain, which is known to play an important role in the work of consciousness, we have learned to register the electrical activity of neurons, while the subject performs some task that requires conscious attention. Let’s say that we have found cells in which an action potential arises when I consciously see red flowers on a rose bush at Wave Hill Estate. Thus, we took the first step in the study of consciousness, namely, we found what Crick and Koch called neural correlates of consciousness for the perception of this object. For most, this will be a big step forward, because it points to a material unit associated with conscious perception. After that, we can go further and set up new experiments to determine whether such correlates merge into a single coherent whole, that is, whether they combine the image of a rose bush with images of the Hudson River and the cliffs on its other shore. But Nagel and Searle believe that this is the simplest of the two problems of consciousness. A more complex one is the second riddle, the riddle of subjective experience. How is it that I react to the image of a red rose with certain feelings that are characteristic of me? Or, if we consider another example, what grounds are there to believe that when a mother looks at her child, the signals transmitted by neurons in the area of the cortex of her brain associated with the perception of faces are responsible for the emotions she experiences and for her ability to recall these emotions and the image of her child? We still do not know, even in the simplest cases, how the signals of individual neurons provide the subjective component of conscious perception. Moreover, Searle and Nagel argue that we do not yet even have a suitable theory of how an objective phenomenon, such as electrical signals in the brain, can provide a subjective experience, such as the sensation of pain. And because modern science is reductionist, analytical the concept of complex phenomena, and the subjective nature of consciousness cannot be simplified, is still beyond our reach. According to Nagel, science cannot undertake the study of consciousness without making significant changes in its methodology that will allow scientists to identify and analyze elements of subjective experience. These elements are most likely the basic components of the brain (just as atoms and molecules are the basic components of matter), but we still cannot imagine the form in which they exist. Nagel argues that the problem is not related to the reduction that science constantly resorts to. Science can easily explain how the properties of a certain type of substance arise from the objective properties of its constituent molecules. But science has no rules that would explain how the subjective properties of consciousness arise from the objective properties of neurons connected to each other. At the same time, Nagel argues that our complete lack of understanding of the elements of subjective experience should not prevent us from finding neural correlates of consciousness and rules that connect the phenomena of consciousness with the processes occurring with brain cells. Moreover, only the accumulation of such information can allow us to figure out how to reduce something subjective, reducing it to the material and objective. But in order to arrive at a theory that supports such a reduction, we will first have to discover the elements of subjective consciousness. This discovery, according to Nagel, will be an achievement of great significance, will require a revolution in biology and, most likely, a complete transformation of scientific thought. Most neuroscientists involved in consciousness research set much more modest goals for themselves than this grand plan suggests. They do not seek to revolutionize scientific thought and do not expect such a revolution. Although they have to overcome the difficulties associated with the experimental definition of consciousness phenomena, they do not see these difficulties as obstacles to any experimental studies of consciousness within the framework of existing models. Neuroscientists believe, and Searle agrees with them, that they have achieved considerable success in elucidating the neurobiological nature of perception and memory, even without taking into account individual experience. For example, cognitive neuroscience has advanced in elucidating the neural basis of blue perception, without asking how each of us reacts to the same blue color. But we have not yet been able to understand the complex problem of consciousness — the mechanism of the emergence of subjective experience from neural activity. Crick and Koch argued that when we solve a simple problem (the problem of unity of consciousness), we can experimentally manipulate neural systems to solve a complex one. The problem of unity of consciousness is a variant of the problem of binding, first formulated in the course of research on visual perception. An integral part of the subjective pleasure I feel when I look at the roses at Wave Hill Estate is how the sight and smell of these roses connect with each other, combining with the view of the Hudson River, the cliffs on its shore, and other components of the picture I perceive. The existence of each of these components is provided by different parts of the visual, olfactory, and emotional systems of my brain. The unity of my conscious experience suggests that this bonding process must somehow connect and integrate different areas. To take the first step towards solving the simple problem of consciousness, we need to ask ourselves whether the unity of consciousness (which, we believe, is achieved through neural systems that provide selective attention) is localized in one or a few places. If so, it would give us the opportunity to manipulate the unity of consciousness using biological methods. The answer is by no means obvious. Gerald Edelman, one of the leading theorists of the problems of the brain and consciousness, argued that the neural apparatus that ensures the unity of consciousness is most likely widely scattered throughout the cortex and thalamus. As a result, Edelman argued, it is unlikely that we will be able to find consciousness in some small set of neural correlates. Crick and Koch, on the contrary, believed that the unity of consciousness would have direct neural correlates, because its mechanism probably involved a special set of neurons with specific molecular or neuroanatomic features. They argued that these neural correlates seem to require only a small number of neurons operating like a spotlight, directing the beam of selective attention. According to them, our initial task is to find out exactly where in the brain this small set of neurons is located, the activity of which best correlates with the unity of conscious experience, and then identify the neural circuits that these neurons are part of. But how do we find a small population of neurons that can ensure the unity of consciousness? What criteria should these neurons meet? In their last article (which Crick continued to edit on the way to the hospital a few hours before his death on July 28, 2004), Crick and Koch suggested that the area that ensures the unity of our experience may be the so—called fence – a layer of brain tissue located under the cortex. Little is known about the fence, except that it is connected to almost all sensory and motor areas of the cortex, as well as to the amygdala, which plays an important role in the work of emotions, and exchanges information with all these structures. Crick and Koch compared the fence to a conductor leading an orchestra. Indeed, the neuroanatomical connections of the fence satisfy the requirements that can be presented to the conductor: they are able to connect and coordinate the work of various parts of the brain necessary for the unity of conscious experience. The idea that Crick was so passionate about at the end of his life (that the fence plays the role of a center of attention — a place where various components of perception connect together) was the last of a number of important ideas he put forward. Crick’s enormous contribution to science (the double helix of DNA, the nature of the genetic code, the discovery of messenger RNA, the mechanism of synthesis of protein amino acid sequences on the messenger RNA matrix, and the introduction of consciousness biology into its own rights) puts him on a par with Copernicus, Newton, Darwin, and Einstein. But his deep, lifelong passion for science and the existence of reason is shared by many members of the scientific community. This kind of passion is typical of science at its best. Vilayanur Ramachandran, a cognitive psychologist, a friend and colleague of Crick, described Crick’s fascination with the “fence” in the last weeks of his life.: “Three weeks before his death, I visited him at his home in La Jolla. He was eighty-eight, dying of cancer, suffering from pain and undergoing chemotherapy, but it was clear that he was spending the rest of his energy continuously working on his latest project. His large desk (which occupied half the room) was covered with articles, letters, envelopes, recent issues of the journal Nature, a laptop (despite his dislike of computers) and the latest books on neuroanatomy. During the two hours that I spent with him, there was not a single mention of the disease, just a flight of ideas about the neural foundations of consciousness. He was particularly interested in a tiny structure called the “fence,” which he felt had been unnecessarily neglected by traditional scientists. When I was about to leave, he said to me, “Rama, in my opinion, the secret of consciousness is in the fence, what do you think? Otherwise, why would this tiny structure need so many connections to different sites?” And he gave me a sly, conspiratorial wink. It was our last meeting.” Since so little was known about the fence, Crick wanted to establish an institute that would study its functions. In particular, he wanted to find out whether the fence turns on when the unconscious, subthreshold perception of a certain stimulus by the human senses turns into a conscious sensation. One example of such transitions that interested Crick and Koch concerns binocular competition. In this example, a person is shown two images at the same time (say, vertical and horizontal stripes) in such a way that each eye sees only one set of stripes. The subject’s brain can combine these images, and then the subject will say that he saw a grid, but usually people see one image or another, so the vertical and horizontal stripes spontaneously replace each other. Using magnetic resonance imaging, Eric Loomer and his colleagues from University College London have found that when a person’s conscious attention switches from one image to another, certain areas of the frontal and parietal lobes of the cortex are activated. These areas play a special role in the concentration of conscious attention on objects that have a certain position in space. The prefrontal cortex and the posterior part of the parietal cortex seem to relay the decision of which of the images perceived by the visual system to enhance, which leads to the appearance of the corresponding image in consciousness. In this regard, people with damage to the prefrontal cortex have difficulty switching from one image to another in experiments with binocular competition. Crick and Koch could have assumed that the areas of the frontal and parietal cortex obey the fence, which switches attention from one eye to the other and forms a single image that enters consciousness from each eye. From the above it is clear that the problem of consciousness is still very far from being solved. But thanks to the efforts of Edelman, on the one hand, and Crick and Koch, on the other, we now have two specific testable theories at our disposal that are worth exploring further. Source: Theory and Practice