Authors: Daniel Bor
The Ravenous Brain: How the New Science of Consciousness Explains Our Insatiable Search for Meaning (39 page)
BOOK: The Ravenous Brain: How the New Science of Consciousness Explains Our Insatiable Search for Meaning
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What of the second form of ethical system, where any discussion of rights is ignored, and all that matters is the net pleasure and suffering in a population? To illustrate the details of such an ethical framework, imagine that a million mice each consciously suffered amount
x
in the lab as part of research that could lead to the eradication of a human disease. This sacrifice would be justified if, say, 100 humans are each spared at least 10,000 amounts of
x
in conscious pain, or if at least a million people would no longer each have
x
amount of suffering (in both cases, at least a million amounts of
x
suffering is avoided).
x
in the lab as part of research that could lead to the eradication of a human disease. This sacrifice would be justified if, say, 100 humans are each spared at least 10,000 amounts of
x
in conscious pain, or if at least a million people would no longer each have
x
amount of suffering (in both cases, at least a million amounts of
x
suffering is avoided).
Under this ethical system, we would clearly need, somehow, to be able to quantify the level of consciousness, and therefore the amount of suffering, that each animal actually experienced. Although we are inching toward the ability to calculate conscious levels using current theories and techniques, we are certainly not yet at this scientific stage. However, we should keep our eyes wide open for advances in the next decade or so. Once any practical means of making these calculations emerges, we shouldn’t hesitate to apply these techniques to any part of our culture where animal suffering may be occurring. This way, we would ensure that we were not unduly creating net amounts of suffering in an extended population of all conscious creatures, and that we were guarding against underestimating the conscious levels of other animals while selfishly exaggerating our own capacity for suffering.
Wider ethical issues—for instance, involving abortion and the right to life, as well as artificial consciousnesses—could also be evaluated on the basis of some quantification method for level of consciousness. But it’s worth bearing in mind that for fetuses, despite our intuitions, all the evidence currently suggests that consciousness is highly unlikely before birth. As for artificial intelligence, no computer or robot in the world currently has an architecture that could even provide the smallest form of awareness, let alone allow for suffering, which might even be an entirely distinct issue in artificial life. It might be possible, for instance, to engineer an artificial being that is conscious and motivated, but that lacks the capacity for anything beyond the mildest levels of suffering, because we haven’t programmed it for anything more intense.
DIFFERING QUALITIES AND QUANTITIES OF EXPERIENCEThe two parallel probing streams of this chapter, one behavioral and the other physiological, paint a broadly convergent picture of animal consciousness, though with some marked differences. The behavioral approach, ignoring any hints from brain size, neural complexity, and so on, provides tantalizing provisional clues to consciousness in very many species, possibly even down to the lowly fruit fly with its rudimentary attentional system. But far firmer evidence of awareness, such as when animals recognize themselves in the mirror, or can report on their own level of doubt, is limited only to that handful of species with the largest, most sophisticated brains. It seems reasonably clear from such behaviors that these privileged species can demonstrate an advanced form of consciousness. A little surprisingly, from our usually chauvinistic perspective, that set of species that we would class from their behavior as almost certainly conscious isn’t limited to our closest evolutionary cousins, the great apes, or even a little further afield, to primates and other higher mammals.
The physiological approach sidesteps problems of reliability inherent in making observations of behavior, but it also creates new problems because physiology is a far less direct measure of consciousness than behavior. There is also less scientific consensus about which of these indirect physiological approaches is the most accurate. But perhaps the most promising direction would be something along the lines of information integration theory, where the complexity of a system, regardless of how anatomically similar it is to humans, would be an index of levels of consciousness. On this basis, there would be a continuum of consciousness, with humans, and our most densely interconnected brains, at the top, but some of the simplest animals having some level of awareness as well, albeit a minimal one.
Both the behavioral and physiological approaches suggest that those animals with the largest, most complex neural architecture and the most able minds are the most conscious. But each technique emphasizes a different perspective on the question of nonhuman awareness. The most parsimonious way to marry the two methods is to conclude that there is indeed a continuum of consciousness from humans to the smallest, simplest of creatures, but that within this there are distinct, meaningful steps that emerge out of a deeper sense of awareness. These steps include self-awareness, a sense of doubt, and the ability to build pyramids of meaning within our own minds.
This final skill, unique to humans, may underpin our flair for language. It is reflective of our exceptionally flexible working memory, and is very probably the underlying reason for this nagging sense many of us have that humans really do have a clearly raised awareness compared to any other species.
This explanation for what crucially distinguishes humanity from the rest of the animal kingdom fits neatly with the technological marvels of the modern world that pervade our lives. These advances are a constant reminder of how different we are from other animals. Such a view of our unique qualities could partially explain human evolution. Early precursors to
Homo sapiens
may well have used their fledgling ability to spot patterns to powerful effect, creating primitive technologies that would have been impressive to the tribe and yield a greater variety and quantity of food. A technological and evolutionary runaway effect could easily have occurred, giving rise to the modern human brain, which has an immense, diverse consciousness and a profound, unique ability to chunk information, to notice and exploit deep patterns in nature, and to create all the technological marvels that enrich our lives and make it so much easier to survive than ever before.
Homo sapiens
may well have used their fledgling ability to spot patterns to powerful effect, creating primitive technologies that would have been impressive to the tribe and yield a greater variety and quantity of food. A technological and evolutionary runaway effect could easily have occurred, giving rise to the modern human brain, which has an immense, diverse consciousness and a profound, unique ability to chunk information, to notice and exploit deep patterns in nature, and to create all the technological marvels that enrich our lives and make it so much easier to survive than ever before.
But the price we pay for such a unique, expansive awareness, supported by a supercharged neural machine, is intense fragility. Our large, immensely complex brains can be easily, irreparably damaged, sometimes by just a knock. Such accidents can diminish or even permanently rob us of consciousness. Another form of neural frailty is far more subtle, but also far more prevalent: Genetic or chemical abnormalities in our brains can easily upset our mental balance and breed any one of a range of insidious mental illnesses. In the final two chapters I will describe the often tragic corollary of our collective capacity for deep conscious innovation. I’ll first detail precisely how vulnerable our brains are to significant damage and how current ideas of awareness can help detect what consciousness remains following traumatic brain injury. Then I’ll outline how a dysfunctional consciousness lies at the heart of most forms of mental illness, and close with how the model of awareness espoused in this book can help illuminate a path out of these emotional prisons.
7
Living on the Fragile Edge of Awareness
Profound Brain Damage and Disorders of Consciousness
When recruiting normal volunteers for our neuroimaging experiments, I always ask my potential subjects a series of questions to make sure they are suitable. For instance, because the fMRI scanner is essentially a tremendously powerful magnet, if a volunteer has a metal implant, then even approaching the scanner could be dangerous. We also ask questions designed to ensure that each person in our eventual group of participants has as normal a brain as possible. For instance, we exclude anyone who has had brain tumors, strokes, or any other neurological condition.
But in addition, we rule out anyone who has ever been knocked out, even if it was just for a few minutes. This excludes a large proportion of people, as you’d imagine, since head trauma is a common side effect of participation in sports, for example. But this step is necessary, because the sad fact is that a single concussion can easily cause low-level brain damage. And in about 10 to 15 percent of cases, especially if any later concussions occur, there will be more severe brain damage, causing long-term or even permanent memory and concentration problems. Recent evidence suggests that early Alzheimer’s disease can even be induced.
The huge human brain is particularly susceptible to trauma. Brains have the consistency of jelly, and if we suffer a violent blow to the head, our brains bounce back and forth inside our skulls, twisting and shearing in the process. The wires connecting our neurons stretch and strain, and they are easily damaged. The outer edges of the brain, especially at the front, can scrape against the sharp parts of the inner skull and be destroyed. Almost all other species are far less likely to suffer concussions than humans, because their brains are so much smaller and are not as susceptible to such bouncing, tearing forces.
In addition to our vastly increased risk of concussion, we face the risk of more severe brain damage from a serious blow to the head (or a host of other causes). Impacts can all too often lead to a vegetative state, coma, or even death. Such patients’ brains can look decidedly warped and thinned, with little cortical matter left. Entire lobes can be missing following a fall or car accident. Just looking at the MRI scan, though, cannot prepare you for meeting the patient in person. Severely brain-damaged patients in a vegetative state are normally wired up to a large set of medical machines. Their limbs can be twisted, with the body twitching and writhing intermittently. Unnatural, repetitive movements are common. Although they may have their eyes wide open, and superficially seem awake, a close inspection shows that this is a cruel illusion. There is no real evidence that there is any kind of awareness of the outside world: The patients’ eyes do not seem to focus on important features of their surroundings; their expressions are not responsive to the environment; and there is a general, frightening void when you try to infer their thoughts from any of their random actions. It is a heartbreaking and disturbing sight, and almost more difficult for the family than if the patient were in a coma. With the vegetative state, the outward signs of wakefulness constantly promise a hidden consciousness inside patients’ heads, or at least hope of recovery. But in many cases that hope is false.
Now, knowing what I do about the brain, and having seen such patients, action movies are no longer just the mindless, cartoonish entertainment they were to me as a child: Whenever I watch an Indiana Jones or James Bond film, where countless nameless guards are victims of knockout blows by fists, wrenches, frying pans, and so on, I can’t help wincing a little at each blow. To me, now, these attacks mean millions of neuronal wires being stretched to breaking point.
I’m firmly of the belief that scientific research is worthwhile, purely for the knowledge that we gain about ourselves and the universe, even if that fresh understanding can bear absolutely no practical fruit. But for a question as intimate and profound as “What is consciousness?” it’s almost inevitable that society will benefit from the answer in a multitude of ways.
One of the subfields currently bearing fruit is the research in disorders of consciousness, with vegetative state one of the most prominent examples. Twenty years ago, a patient appearing to be in a vegetative state would have had surprisingly meager help from the medical community, beyond being kept alive. An assessment of just how conscious the patient was amounted to little more than guesswork. The same was true of any prognosis for recovery. Now, for diagnosis and prognosis, at least, the territory looks very different. A large, active research community is working hard to use increasingly mature models of consciousness to quantify the degree to which awareness has been stolen from these patients. Sophisticated predictions of recovery are also emerging. And although treatments are somewhat lagging behind, nevertheless there is tentative progress in this realm as well. In this chapter I will relate the advances that have been made in understanding and treating such severe disorders of consciousness. I will also describe how vegetative state research is reaffirming and extending our current ideas about how awareness functions.
A TORTUOUS BATTLE OF UNCERTAINTYTerri Schiavo was a shy girl living in Florida. By her mid-twenties, with a reasonably uneventful, settled life, she and her husband, Michael, were trying to have children. However, Terri was probably suffering from severe bulimia as she fought to control the weight problems that had been an issue for much of her life. On February 25, 1990, in the middle of the night, Terri’s heart stopped, most likely due to a chemical imbalance caused by the bulimia. The ambulance crew managed to revive her, but too many minutes had ticked away in temporary death, and she suffered massive brain damage.
Terri was in a coma for about three months. Her condition then improved slightly and she entered a vegetative state, where she could open her eyes and show signs of sometimes sleeping, sometimes waking. But this glimmer of hope was painstakingly eroded as it gradually became clear that she would not improve any further.
Eight years after the accident, with no change in her condition, and any remote hope of recovery having long since receded, her husband, Michael, filed a petition for Terri’s feeding tube to be removed so that she could pass away. Terri’s parents, in total contrast to the doctors’ assessment, believed that Terri was still in there somewhere, that she could at times find pleasure in the company of her family, and that she might well recover further with some future treatment. Thus began one of the most famously bitter legal disputes in history.
BOOK: The Ravenous Brain: How the New Science of Consciousness Explains Our Insatiable Search for Meaning
8.72Mb size Format: txt, pdf, ePub
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