The greatest mysteries: What is consciousness?
What is consciousness? Yes, in fact, everything. It's a tune stuck in your head, the sweetness of chocolate, throbbing toothache, wild love, knowing that all feelings ever go out. The origin and nature of these experiences, sometimes called qualia have been a mystery since the earliest days of antiquity to the present day. Many modern philosophers, analyzing intelligence, including Daniel Dennett of Tufts University, believe the existence of consciousness is so blatant insult to the meaningless universe of matter and emptiness, which announced its illusion. That is, they either deny the existence of qualia, or argue that science will never understand.
If this statement was true, we had nothing to talk about. All you need to be explained Kristof Koch, wrote this essay, this is why you and I and all the others firmly believe that the feelings we still have. However, the belief that pain - it is an illusion, the pain is not to downplay. So, there should be another solution to the problem of the body and mind. Then - in the first person.
Most scholars accept consciousness as a reality and seek to understand its relationship to the objective world described by science. More than a quarter century ago, Francis Crick and I have decided to postpone discussion on the philosophical consciousness, which attracted scholars from the time of Aristotle, and look for his physical prints. What happens to the excited portion of the brain substance that produces consciousness? Once we understand this, we get closer to the solution of a more fundamental problem.
We are seeking, in particular, the neural correlates of consciousness (NCC, NCC), defined as the minimal neural mechanisms, which will be enough for any particular conscious experience. What should happen to your brain that you've experienced a toothache, for example? Should some of the nerve cells to vibrate at a certain frequency of magic? some special "neurons of consciousness" Do I need to activate? In which areas of the brain must be in these cells?
The neural correlates of consciousness
In determining the NCC, it is important to understand where the minimum. The brain as a whole may be considered NCC: it generates the experience of day-to-day, non-stop. But the location of the mind can be further fenced. Take, for example, the spinal cord - a long and flexible "hose" with neurons, wedged into the bone, with the billions of nerve cells. If the spinal cord is completely damaged during the injury in the neck, a man paralyzed in the legs, arms and torso, he would not be able to control the bowel and bladder, and lose the sense of the body. But such paralyzed continue to enjoy life in all its diversity - they see, hear, smell, feel and remember everything the way it was before the unfortunate incident. Just can not go, well, they defecate freely.
Or let's look at the cerebellum, a "little brain" under the rear part of the brain. This is one of the most ancient brain circuits from the point of view of evolution, involved in motion control, posture, gait and complex sequences of movements. Playing the piano, print, ice dancing or climbing - all these activities are determined by the work of the cerebellum. There are great neurons - Purkinje cells, which have antennae and are distributed like marine corals and possess complex electrical dynamics. Also it most neurons, about 69 billion, four times higher than in other parts of the brain put together.
What happens to the mind when the cerebellum partially damaged as a result of stroke or under the surgeon's knife? Never mind. Patients with damaged cerebellum complain of some deficiencies, it is not as well play the piano or typing on the keyboard, but never lose any aspect of consciousness. They hear, see and feel fine, preserve self-esteem, remember events of the past and continue to project itself into the future. Even the birth without the cerebellum does not have a strong influence on the conscious experience of the individual. It turns out a huge cerebellar apparatus is irrelevant to the subjective experience. Why? Important tips can be found in his scheme, which is extremely uniform and parallel (in the same way as the battery can be connected in parallel). Cerebellum works quite straightforward: one set of neurons affects the next, and he passes the baton to the third. There are no complex feedback loops, which are reflected in passing electrical activity. (Given the time required for development of conscious perception, most theoreticians believe that it should include a feedback loop in the cavernous circuits of the brain). Furthermore, cerebellum functionally divided into a hundred or more independent computing modules. Each of them operates in parallel with individual, non-overlapping inputs and outputs, controlling the various movements of motor or cognitive systems. They interact weakly - and consciousness, on the contrary, requires mutual engagement multiple systems.
One important lesson we have learned by studying the spinal cord and cerebellum, is that consciousness is not a genie appears whenever instituted any neural tissue. Need more. This additional factor is found in gray matter constituting famous cerebral cortex, the outer surface thereof. This laminated sheet complex, interconnected neural tissue, the size and width with a 14-inch pizza. Two of the sheet, folded several times, with their hundreds of millions of wires - white matter - tightly crammed into the skull. Everything indicates that the neocortical tissue gives rise to feelings.
You can further narrow down the location of consciousness. Take, for example, experiments in which different stimuli affect the right and left eyes. Suppose the left eye looks at Donald Trump and the right to Hillary Clinton. One would imagine that people would see the superposition of Trump and Bill Clinton. In reality, you'll see Trump a few seconds, then it will disappear and Clinton appear. Then it will disappear and return to Trump. Two images will be rotated endlessly because of binocular rivalry - the war between the eyes for the championship. As the brain receives a dual input, it can not choose between Trump and Bill Clinton. If, at the same time, you will be in a magnetic scanner, which records brain activity, the experimenters will find that a wide range of areas of the cortex - posterior parietal cortex - will play a significant role in seeing to it that we see. Remarkably, the primary visual cortex, which receives and transmits the information received from the eyes, does not indicate that the subject sees. The same division of labor is true for sound and touch: the primary auditory cortex and primary somatosensory do not directly affect the contents of the auditory or somatosensory experience. Instead, the process comprises the following steps - in the core posterior parietal cortex - which gives rise to the conscious perception.
More shed light source two clinical causation: electrical stimulation of tissue in the cortex and study of patients after loss of specific areas in the process of injury or disease. For example, before removing the brain tumor or locus seizures, neurosurgeons function mapped nearest cortical tissue directly stimulating its electrodes. Stimulation of the rear of the hot zone may cause the flow of various emotions and sensations. These may be flashes of light, geometric shapes, faces, auditory or visual hallucinations, a sense of deja vu, the desire to move a particular limb, etc. Promoting the front part of the crust - is another matter:.. By and large, it does not cause any direct experiences.
The second source of information - neurologists, patients with the first half of the 20th century. Sometimes surgeons had to cut a large zone of the prefrontal cortex to remove the tumor or to relieve epileptic seizures. What is remarkable is how unusual these patients. The loss of the frontal lobe had some harmful consequences: patients developed unwillingness to restrain unacceptable emotions or actions, motor deficit, uncontrollable repetition of words or actions. However, after the operation he was getting better, and they continued to live without any signs of loss or deterioration of conscious experience. In contrast, the removal of even small areas of the back of the cortex, where the hot zones could lead to a whole class of problems with consciousness: patients can not recognize faces, detect motion, color or orientation in space. Thus, one might think that looks, sounds and other sensations of life that we experience, born in the posterior cortex areas. As far as we can tell, almost all conscious experiences appear there. What is the fundamental difference between these regions and the rear most part of the prefrontal cortex, which does not directly affect the contents of the subjective? We do not know. However, the recent discovery indicates that neuroscientists may be close to unraveling.
Medicine needs a device that can reliably detect the presence or absence of consciousness in people disabled or impaired. During surgery, for example, patients are immersed in anesthesia to remain stationary and stable blood pressure - it allows them to not feel pain, and do not acquire a traumatic memories. Unfortunately, this goal can be achieved is not always: every year hundreds of patients somehow remain in the consciousness under anesthesia.
Another category of patients who have severe head injury due to an accident, infection or severe poisoning, can live for years without being able to speak or respond to verbal requests. Imagine an astronaut floating in space, who listens to the control center, trying to reach him. It damaged the microphone is not transmitting voice, and he seems to be completely detached from the world. Similarly, patients with brain damage, not allowing them to communicate with the world, feel the extreme form of solitary confinement.
In the early 2000s, Giulio Tononi of the University of Wisconsin-Madison and Marcello Massimino from the University of Milan in Italy, invented the zip-zap technique to determine, in the mind of the person or not. Scientists put the coil wires at the skull and "shoot through" her - send a powerful impetus to the skull of magnetic energy, briefly inducing an electric current in the neurons. This intervention, in turn, excites and inhibits neuronal cell partnership in connected areas, wave sweeps through the brain until it dies out. EEG sensor network located outside the skull, reads the electrical signals. Unfolding over time, these tracks, each of which corresponds to a specific location in the brain under the skull, are added to the picture. This picture does not show any laws, but is not completely random. It allows you to determine how the brain is free from the consciousness of rhythms. Scientists have quantified the data, compressing them in a conventional algorithm archive .zip, and get the complexity of the brain's response. Volunteers who awoke had "disturbing complexity index" of between 0, 31 and 0, 7, which fell below 0, 31 during deep sleep or anesthesia. Massimino and Tononi tested his method on 48 patients who had brain damage, but have been responsive and awake, and found that in each case the method to determine the presence of consciousness in humans.
The team then applied the method to the 81 patients who were minimally conscious, or have been in a vegetative state. In the first group, which showed some signs of non-reflexive behavior, the method accurately identified the 36 people in the minds of 38. Two patients were unconscious he mistakenly marked. Of the 43 patients in a vegetative state who did not respond, 34 were labeled as unconscious, but 9 - conscious. Their brains responded similarly to the brains of those who were in the mind, and therefore they were conscious, but could not report it to their loved ones.
Current research is focused on the standardization and improvement of the method "zip-zap" for neurological patients and distribute it to patients of psychiatrists and pediatricians. Sooner or later, the scientists find a specific set of neural mechanisms that give rise to some conscious experience. Although these findings will have important clinical implications, and help families and friends, they will not be able to answer the fundamental questions: why these neurons, rather than those? Why at this frequency, and on the wrong? Exciting all secret is how and why any organized slices active substances produce conscious sensation. After all, the brain is like any other organ, is subject to the same laws of physics as the heart and kidneys. What makes them different? What is biophysics turns gray mass of gray matter in the grand Technicolor and richness of sound that belongs to our everyday experience with this world? Ultimately, we need a satisfactory scientific theory of consciousness that will predict the conditions under which any single physical system - be it a complex circuit of neurons or silicon transistors - began to experience in the truest sense of the word. Why is the quality of these experiences will be different? Why is the clear blue sky is so different from the screeching violins in a bad mood? Is there a function of these differences in experiences, and if so, what kind? Such a theory will allow us to determine what the experience will be in a single system. Before it appears any talk of machine consciousness will be based solely on our intuition, which, as the history of science, an unreliable guide.
Particularly heated debate broke out around two of the most popular theories of consciousness. One of them - the theory of global neural space (GNW), developed by psychologist Bernard Baars and neurobiology Stanislas Dehaene and Jean-Pierre Shango. The theory starts with the postulate that when you become aware of something, this information can access many different parts of your brain. If, on the other hand, you act unconsciously, the information is localized in a particular sensory-motor system involved in the process. For example, when you print faster, you do it on the machine. I ask you how you do it, and you can not answer, you almost do not have conscious access to this information, and it is concentrated in the brain circuits that bind your eyes with a quick movement of his fingers.
In the direction of the fundamental theory of
According GNW, consciousness arises from a particular type of information processing - is familiar with the early days of artificial intelligence, when the specialized program have access to a small, divided repositories of information. Regardless of the data recorded on this "board", became available to the various sub-processes: working memory, language, planning module, and so on. According GNW, consciousness occurs when part of the sensor information recorded on this board, widely broadcast in different cognitive systems - that process the data for a conversation, save, or memories of the action. Since this board is not much room, we realize at the same time not so much information. network of neurons that transmit these messages are believed to be located in the frontal and parietal lobes. After sparse data broadcast network and made available globally information is realized. That is, the subject is aware of it. Although modern cars have not yet reached this level of cognitive complexity, it is only a matter of time. GNW implies that future computers will be conscious.
Integrated information theory (IIT), developed by Tononi and his colleagues, including myself, has a completely different starting point: an experience in itself. Every experience has certain essential properties. He is the inner, exists only for the subject for the "owner", it is structured (yellow bus slows to a dog ran across the road), it is concrete - it can be distinguished from other conscious experience as a single frame in the film. In addition, it is a common and specific. When you sit on a park bench in warm, comely day, watching the children playing, the different parts of this experience - the breeze, singing in your hair, the joy of laughter to your baby - can not be divided into parts, without losing the fullness of the experience.
Tononi postulates that any complex and interrelated mechanism, the structure of which encodes the plurality of causal relationships will have these properties - and, therefore, will have some level of consciousness. If, as the cerebellum, this mechanism is not enough integration and complexity, he did not realize it. According to the IIT, consciousness is an internal causal force, which have complex mechanisms such as the human brain.
IIT also predicts that the complex modeling of the human brain, working on a digital computer, may not be conscious - even if it is talking so as not to be distinguished from a real person. Just as the simulation of a massive gravitational pull of a black hole will not distort space-time around a computer, consciousness, programming will never create a conscious computer. We are faced with two problems. One of them is to use more sophisticated instruments to observe and investigate the neurons, seek consciousness in these neurons. It will take decades, given the Byzantine complexity of the central nervous system. Another objective was to confirm or refute the two dominant theories. Or create a better on the ruins of the two and explain how polutorakilogrammovy body gives us the fullness of sensations.