Mystery of the Brain

      

By Nassir H. Sabah

Although a great deal is known about the properties of the constituents of the brain, the overall functioning of the brain is still a mystery. It seems that understanding the functioning of the brain requires a radical paradigm shift from our current framework of thinking about the brain.        In fact, we understand more about the cosmos and sub-atomic structure than about the workings of this fatty blob that we call our brain. Tremendous efforts to unravel the mysteries of the brain have been made over the past century or so by a multitude of talented and highly trained researchers in many countries using an impressive array of increasingly sophisticated tools and techniques.      An enormous amount of information has been accumulated about the basic constituents of the brain: the brain cells and their components, their structure, the way they function, and the electrical and chemical signaling between them. What is still largely unknown is how does all this translate to meaningful, overall brain function. It’s like having a great number of pieces of a gigantic jigsaw puzzle without being able to fit them together.      Consider, for example, one’s decision to move one’s hand to scratch one’s head. It is well known that one of the first physical manifestations of this movement is an electrical signal that appears in a part of the brain, followed by a whole cascade of chemical and electrical signaling that eventually results in the appropriate pattern in time of tiny electrical pulses – known as action potentials – that are distributed spatially over thousands of nerve fibers so as to cause the right muscles to contract and execute the required movement.      Although this seems like a simple movement that we perform without thinking about it, it is actually quite complex when analyzed. For one thing, a number of joints are involved: shoulder, elbow, wrist, and several finger joints. Since muscles can only pull and not push, movement at each joint is controlled by two opposing sets of muscles – the so-called antagonist muscles – that should all be properly activated by these patterns of action potentials so that the whole movement is appropriately coordinated between the various joints and muscles for it to be executed with seamless precision and eventually brought to a stop.      What directs the fingers to the desired location on the head – usually somewhere above and to the side of the forehead – and not strike the nose, or be directed to the eyes or ears? What makes the finger movement gentle enough so as not to bleed the scalp with the fingernails? We can make the movement with our eyes closed, so that vision need not be involved.      What is involved are our senses of proprioception – that is, our unconscious perception of movement and spatial orientation mediated by specialized receptors in joints, muscles, and tendons – as well as our sense of touch. The brain must generate the required spatiotemporal pattern of action potentials, monitor the movement, and make corrections on the fly, as in the case of some unanticipated impediments, such as a tight-fitting jacket, for example.      How the brain does all this has only been postulated rather vaguely, with no general agreement among investigators as to how the movement is planned and executed. Moreover, what is often glossed over is how does this volitional act of wanting to scratch one’s head – which is a mental activity, that is, something purely in the mind – generate a physical electrical signal in the brain in the first place?      And this is just concerning movement, whose end result is amenable to observation and precise measurement. When it comes to perception and consciousness, matters are much hazier. If a red rose if placed under the nose, for example, with eyes closed, one would recognize a rose from the fragrance. When the eyes are opened, red light impinges on the retina of the eyes and generates in some of the retinal cells electrical signals that travel to the brain along well-defined neural pathways.      These electrical signals are processed in parts of the brain, in a manner that is at present largely unknown, so as to perceive a red rose with its characteristic rounded shape and its petals overlapping in three dimensions. The sight and fragrance of the rose might evoke memories of a bouquet of red flowers on some happy occasion, which might in turn bring some feelings of nostalgic joy.      The perceptions of the smell and color of the red rose and the memories and feelings evoked are subjective – that is, in the mind – and are unique to each individual. No two people would sense the same smell or perceive the same vividness of color or experience the same feelings upon the sight of the red rose. This is part of our consciousness as unique human individuals. To say we have a good inkling of how the brain does all this is a rosy view in the extreme.      Speaking of memories, this is yet another mystery of the brain. Memory is of course essential to our existence. Without memory, we would hardly be able to do anything useful, will not be able to use any information we have acquired, knowledge we have gained, or skills we have learned. We would not remember our own names or recognize the looks and voices of our family members, friends, and associates, or be able to read or write, or maybe even talk or walk!      But where and how memories are stored remains elusive. It has long been assumed that memory is stored by some changes in the brain, referred to as memory traces or engrams. Yet, all attempts at definitive identification and localization of these memory traces have failed so far to give satisfactory and generally accepted results. Nearly a century ago, the American neuropsychologist Karl Lashley attempted to locate the areas and pathways in the brain that support visual discrimination and maze learning in rats. In a classical series of experiments, Lashley trained rats to run a maze. He then removed portions of their brains and retested them to see if the memory of what they have learned was lost. To his surprise he found that no matter which relevant part of the brain he removed, the rats retained the memory, even with fairly massive removals, although the degree of impairment in maze performance increased with the amount of brain tissue removed.      This suggested to the American neuroscientist Karl Pribram that memory was distributed in the brain and was of a holographic nature. A hologram of a three-dimensional object is a two-dimensional recording, on a photosensitive plate or film, produced by a laser beam part of which is applied to the photosensitive medium and the other part is reflected by the object onto this medium. The two beams converging on the photosensitive medium interfere with one another producing an interference pattern that is recorded in the medium. When the same laser light used in the recording is shined on the recorded interference pattern a three-dimensional image of the object is reproduced. One can move around the image and view it from different angles, as with the real object.      A remarkable property of the hologram is that a piece of the hologram can reproduce the image of the whole object, albeit with some blurring that increases as the size of the piece is reduced. This means that every part of the hologram contains information about the whole object, that is, the information about the object is distributed throughout the recording in a manner that allows any part of the recording to reproduce the image of the whole object. However, it could not be demonstrated how the brain performs the mathematical transformations underlying holography. The search for the engram continues.      That brain operations are hypothesized to be the likes of technologies of the time is not new. It is an “aha” moment that is but a lame substitute for some original thinking. In the 17th century CE, the French philosopher, mathematician, and scientist René Descartes conceived of the nervous system as a hydraulic system. Animal spirits would flow from the ventricles of the brain through hollow tubes – the nerves – to muscles, filling them up and causing muscular contraction.      After telephone exchanges became operative in the late 19th century CE, the brain was considered to act as a telephone switchboard that switches connections between incoming and outgoing pathways. With the advent of computers, the brain was likened to a computer performing some complex computations. Movement is thought to be executed as a sequence of commands in a motor program, like the set of instructions in a computer program. So, it is not surprising that with the invention of holography the brain was considered in terms of a hologram.      With its power consumption of about 20 watts, the human brain is an energy guzzler, relatively speaking, considering that the whole body consumes about 100 watts, but at 1.3 to 1.5 kilograms, the mass of the brain is only about 2 percent of typical body mass. The human brain grew in size over a span of some two million years, from the earliest human species to our own species, Homo sapiens (the wise humans), despite its energy demand. Some adaptations of the human body are believed to have taken place to cater for this demand, in addition to having to spend more time to procure food.      Other high-energy consuming organs of the body were reduced in size, mainly muscle and intestines. Cooking helped in several ways. A wider range of foodstuff became available, and less energy was required for digestion, which allowed shorter, less energy-consuming intestines. The returns for the larger brains were meager for a long time, mainly some primitive tools such as pointed sticks and sharp stone. So, what was the drive for larger brains? No one really knows. Then between 70,000 and 30,000 years ago in what has been dubbed the “cognitive revolution” or “the great leap forward”,  some chance mutation is believed to have occurred in the brain, with dramatically far-reaching results.      One was a highly developed language that allowed effective communication and the transfer of a tremendous amount of detailed information. More important is imagination, that is, the ability to form mental images, thoughts, and sensations of things and entities that are not physically real. With accompanying developments in the rest of the neuromuscular system, humans acquired amazing and unsurpassed manual dexterity.      The triad of creative imagination, language, and manual dexterity was a formidable combination that propelled Homo sapiens to become the undisputed masters of planet Earth in a matter of 50,000 years or so. Not only were all other human species driven to extinction by Homo sapiens but nearly half of the planet’s large terrestrial animals suffered the same fate by the time of the Agricultural Revolution about 12,000 years ago. And all that just because of a chance mutation in the brain? Many people, including myself, find this very hard to believe, which only adds to the mysteries of the brain.      So where does this leave us? Many scientists have come to the conclusion that to understand brain function, a radical paradigm shift is required. One line of thinking is suggested by the analogy of a television (TV) set. A person who is unfamiliar with broadcasting and the generation, propagation, and reception of electromagnetic waves (like someone suddenly resurrected from a past era) would reasonably assume that what is seen on a TV screen is generated in the TV set itself. This view is supported by the fact that any tinkering with the components of the TV set will generally affect the image on the screen or might obliterate it altogether. But in fact, the TV set is just tuning to an outside signal and is merely processing this signal into a form that can be perceived by the viewer.      Similarly, brains may be tuning to, and merely processing, “something external”. “External influences” have been postulated by biologists and physicists in different contexts, as will be explored in a future article, but have been ignored by brain researchers so far. Why? This recalls the story of the man who lost his keys in a dark alley but went to look for them under the streetlamp, where there was light. The fact of the matter is that no one at present seems to have an inkling of how to investigate such external influences.      In conclusion, the deep mysteries of the brain have so far defied all efforts at unravelling them. But hope springs eternal despite a nagging, somewhat philosophical, tantalizing question: are the thought processes of the brain able by themselves to understand the operations of the brain, or does this understanding require something of a higher order of capacity than the human brain? Will AI do the trick?     https://nassirsabah.com