Computer scientists seek to create an artificial brain every bit as powerful as the human brain, maybe even more powerful, without the drawbacks of the human body, a disembodied brain. But the brain is quintessentially biological, an organ among organs. It is intimately and immanently connected with bodily function. Demise of the body immediately leads to the brain’s own end.  As everyone knows, the brain is the most delicate organ in the body. While it is protectively confined within bone and meningeal coverings, which range from a tough fibrous outer membrane to a more delicate spidery middle, then a  most delicate thin membrane that faithfully follows the cortical convolutions, it is worth pointing out that the brain substance itself is soft compressible mush. The brain rapidly ceases its function if deprived even for a short time, of biological necessities such as blood supply, oxygen, and glucose for energy. Other organ systems will not be damaged in nearly such a short time.

For example the brain is the only organ that requires a constant blood supply in both systole, with the contraction of the ventricle of the heart, and diastole, during relaxation of the heart. The heart itself is somewhat of an exception as blood flows in through the coronary arteries as the muscle relaxes. All other organs get their blood supply with the contraction of the heart muscle as blood gushes out of its chambers.   But the brain alone gets bloodflow in both phases of the heart cycle,  even while the heart relaxes in diastole, If that didn’t happen all of us would faint at each relaxation of the heart.  Should you monitor blood flow to the brain, you would see how blood flows into the brain continuously, making the brain unique among all organs. This shows just how intimately the brain is tied to the body and dependent at all times on bodily function. Some of us may still hold onto the Cartesian notion of a separate mind and body, but if the physicality of the mind is represented in the brain, brain and body are in no way separate. They are more intimately tied together than was ever dreamed, in the mind of an armchair philosopher. Someone asked in the Reign of Terror upon Guillotining, whether in the final moments of life, the brain missed the body or the body pined for the brain. As far as we know, the brain loses consciousness immediately and the body is not conscious, but they function as a tight unit, now severed. Alas, it was the early scientific efforts of  French neurologists of the nineteenth century, that revolutionized the study of the brain.

As far as the brain is concerned, you cannot separate it from the body. The relationship with the body is most intimate and immanent. I use the word immanent in the religious sense, just as some people do in relation to a deity who suffuses and is inseparable from men (as in Deism),  as opposite to the other religious point of view where the god figure hovers outside the World. As a neurologist clinician I have spent my whole professional life protecting the brain as internal organ. If I have learned anything it is how co-dependent brain and body are. The brain has some controlling influence on the body, if only because it is so dependent, more dependent than any other organ, on intact function of the physical body. Should the body fail to supply the brain with its needs even for a second, out goes the light. Consequently most of my time is spent trying to guarantee the homeostasis of the brain by controlling such things as its ionic milieu, and blood supply, maintaining along with my other medical colleagues the health of the whole body.

The heart has left and right sides. The left atrium and ventricle nourish the whole body while the right pumps blue blood to the lungs so it can become red with oxygen. The skin is the largest organ of the body and each patch covers and protects its own portion of the body. But the brain is unique in that all parts of the body are represented, not just once but over and over again, on specific volumes of brain in what are known as projections.

The best illustration of projection of one’s own body onto brain is the inner deformed little man or homunculus  familiar to students of anatomy and medicine. This was confirmed by pioneering experiments by Wilder Penfield  on live patients in the 1940s-50s. Penfield stimulated the cortex of the brain with low voltage electrical probes. The most specific results were obtained around the central sulcus of the cortex. Stimulating patches behind the central sulcus (the parietal lobe) of the brain caused patients to have sensations in specific parts of their body, for instance they might feel a tingle on the thumb in one location, over the lip of their mouth in another, on one toe in another. Using this technique it was possible to map specific areas of the body onto specific sites in the brain, so that patches of brain were found to be somatotopic. Each body part is projected to a specific patch of cortex on the opposite side of the body, right body to left brain. Exactly the same bodily representation occurs for motor function just anterior (in front) of the central sulcus in the frontal lobe. Penfeild found that stimulating a specific area would cause contraction of muscles in one part of the body represented in that area. Nowadays it is possible to stimulate regions of cortex without even opening the skull using magnetic currents, making possible the familiar drawings of little men, homunculi. If you wanted to you could draw loads of these homunculi accurately all over the brain. Your body is represented over and over again and for many different sensory and motor modalities within your brain. Some neurons respond to sensations only of a specific type or modality for example touch or position sense. Other cells have a multi sensory response.  Some areas of the body like hands and mouth and thumb take up disproportionately large regions of brain.  That’s because language and hand function have more neurons devoted to their function, more computational power.   Places like the buttocks, while large on some persons bodies, require much less attention. Generally with increased distance from the central sulcus going backward or posterior, sensory phenomena, while still localized over the body, become more and more abstract and multi sensory. Stimulation with an electric probe might bring up a whole multi sensory experience, like a birthday party, with its own sights, smells, feelings and so forth. Motor representations function in much the same way, as simple movements are replaced with whole motor patterns, and still farther afield plans and aspirations.

What this tells us is that the brain is not separate from the body in the classic Cartesian sense as with Rene DesCartes and countless others who refer to a soul separable from the body. It proves the opposite, that the brain is intimate with one’s body projected over and over again on structures not only over the cortex but through pathways conducting electrical impulses to the brain, over the cables called tracts and in way stations such as the thalamus. Not only are body surfaces projected to specific areas in the brain but the workings of inner organs, like the heart, is projected into an area deep in the temporal lobe, the insula in a sort of cardunculus analogous to the bodily homunculus. Those nutty notions of reflexology where body parts are represented on your foot, or acupuncture over your ear, actually do apply to the brain.

But it doesn’t stop there.  The intimacy of the brain is expressed in its control over endocrine, ductless gland function via the hypothalamus and pituitary. I could go on and on but will will restrain myself, as by now I have conveyed the basic notion that your brain is not a separate cognitive instrument but is intimately associated with its biological container that is you. You are projected over and over again, onto your very own brain. I say your own brain for a reason. You and I have our very own living unique identities and personal experience. Despite so many attempts to prove the contrary, as regards, notions of possession, witchcraft, demonology, multiple personality disorders and other paranormal “phenomena” even split brains, you may have read about,  no one has ever shown to a scientific standard that any more than one unique identity inhabits one individual head or for that matter that there is ever more than one single entity in any one particular biological organism of any kind, (Some might say conjoined twins may be an exception as they do share parts of one body. But if they have two brains, they are two people.)  There is no more than one identity in a Paramecium, plasmodium, any animal or plant, a wolf a dog or human. Each of us, even identical twins, are unique.

The brain’s projections do not stop with our own bodies.  External reality is mapped into and modeled by our own brains.  Reality outside the brain is also topographically represented and like our bodies is multiply projected onto specific locales. The brain’s relation to one’s own unique body is most intimate but so is the brain’s relation to one’s immediate environment  Vision in the right side of our environment is projected onto the occipital  rear facing) lobe of the brain on one’s left, specific places represented over specific cortical areas.  Over what is called the primary visual cortex there is a one to one mapping with points in one’s visual environment.  Macular or central vision is represented on both sides and again over and redunctantly represented in neuronal number. Primary auditory cortex, has tonotopic  representation on the cochlea or hearing organ but this data is projected over the primary auditory cortex, processed along its path, but carried faithfully as are other sensations to representative areas of cortical inner sanctum.  Starting with internal and external bodily sensations and movements, external spatial, auditory, gustatory, olfactory, data are exchanged from outside in and inside out, generalizing from one’s body, to the immanent external world, and finally distant external world,  all of which find topographic specific anatomical projections inside your brain, within our hard skulls, definitive inner representation.

What is the brain then, but an immanent, precise, inner representation, projection, facsimile of both corporeal and extracorporeal reality?  To the extent that this inner representation is useful, likely some “correct” representation, it is advantageous to the owner of the brain, and is therefore worthwhile and adaptive. Should the inner brain or cerebral representation prove ineffectual or inaccurate, it may be maladaptive. When you think of it though, it seems we humans have gone to an awful lot of trouble as owners of brains, which consume about 20% of our energy. The brain has had to construct a whole separate inner model of one’s own body and its environs, a separate inner world.

I talked about sensory and motor inner representation in the brain. The brain is far more than a projection, some sort of inner screen, film, planetarium or what have you. The third part of the brain, after sensory and motor function, is associative. By now, you can see there are are so many localized modules handling sensory and motor functions all of these communicating with one another, we have clusters of clusters of neurons, each devoted to specific modular functions and these communicate.  Vast associative areas of the brain, again in specific anatomical areas, interdigitate. The final product is the personal subjective experience. Individual impressions or qualia combine to create a sense of awareness.  Some huge choral symphonies, Mahler’s Symphony of a Thousand is the best example, require not only an orchestra but multiple choruses. if each chorus is compared to a cluster of neurons that are singing together, a specific part going to each member,  with the high purpose of bringing to life a huge symphonic work,,then consciousness is a Chorus of Choruses. That’s how I see it.

Each of us is aware of how it feels to be ourselves and since our own bodies are projected onto specific parts of our brain, our own inner reality, and unique perspective of how things feel to us, personal experience or inner qualia, are what constitutes what is called consciousness  by which is meant that inner model or representation of ourselves and environs.  Our bodies are unique to ourselves , our experience personal.  There is yet another important projection system that makes this so, that is the limbic system.   Experiences and events are further projected on these deeper gatherings of neurons, I won’t bore you with the names of these anatomical structures except to say they exist,  that color each percept or experience with a value system of emotions, so important to our experience of being conscious entities.   I suspect any machine lacking this internal intimate model with projections upon projections some of which add value and emotional color will be wooden, robotic, lifeless like today’s machines. This is a lesson worth considering in commuter engineers attempts to design  conscious  computational entities. It seems to me the engineers lose sight of the lessons of biology.  In previous posts, i delved into a little bit more, the troubling notion that computers, as currently in use, differentiate data points poorly with very little in the way of values as supplied by our emotional inner human limbic system. The limbic system exists because it serves as an advantageous way of modeling our world. I am aware that software engineers do add some values that differentiate data points, but these are limited to simply prioritizing lists as on Google websites simply arranged by number of hits.

The neurologist separates disorders of consciousness into two components: Arousal and Content. Simply stated some people are not conscious because they are not awake, like being asleep  or under anesthesia. These folks are separated from their environment and fail to experience or respond  to it because sensory pathways are blocked, as in closing the eyes and being insensitive to sounds.  Conscious motor responses to environmental contingencies fail to occur. Arousal circuits in the brain are mostly in the brainstem. An entirely different group of patients are not conscious because of disorders in the cortex. For some,  for example those with advanced degenerative disease such Alzheimer’s disease, a large number of cortical modules are very impaired or have shut down. When some threshold value of cortical real estate fails to function, the person has less than the requisite responsiveness and is unconscious. Many people have compared this with a nighttime view of an office building where most of the lights are off. At some point where you see enough lights tuned off, you will call the building dark i.e. unconscious. Persons with devastating injuries to the brain such as after a subarachnoid hemorrhage or traumatic injury, might end up like this with sleep wake cycles but still being unaware. They have lost too many patches of cortex or cerebral modules. It is difficult to decide exactly when the person crosses the threshold into unawareness as more and more cortical lights turn off. Hence gradations are described such as minimally conscious state.

How does knowing all of this relate to computer models of brain function? Some computer scientists, not all, talk about, reverse engineering the brain. No computer model I have ever read about or seen, has any  or certainly not most, of the characteristics discussed above. As computers don’t have inner projections of their own bodies, or any sense of self, on an inner structure, no intimate and immanent body relationship, but seem to manipulate symbols almost as if in a vacuum, they are fundamentally unlike the brain.  I like to say computers have no skin in the game. Machine computation is of no consequence for any inner self. It goes without saying that living things live and die by their own decision making processes, again, skin in the game. Computers not having that may be a long way from simulating any biological organism.

The brain as such may be unnecessary to many of the processes I discuss above. Simple living things, i mean even protozoa, respond to environmental contingencies on a higher level than do some of our advanced machines and their actions are not simple reflexes, but highly dependent on environmental contingencies. You can observe even the smallest animals either avoid and fight off predators or chase and bring down prey, loco mote to avoid obstacles and efficiently navigate their environments, make allowances for feast and famine, seduce sexual partners, seemingly more complex behavior than observed in any of our advanced robots. Not only do these living things not have brains, though undoubtedly they have control mechanisms intimately tied with their microscopic bodies, but they are no more than pond scum. Most of us know that living organisms ranging from the one cell all the way up to dogs and apes, harbor some form of consciousness.  Many have arousal and content mechanisms built into their brains as humans do, or they need not even have a brain as we know it.  We have some sense that it is wrong to end their life, if we don’t have to, but still have no such qualms about decommissioning any robot or computer.  So come to think of it then may there be some Je ne sais quois, or élan vitale perhaps that it will be difficult to build into a computer?