GRAMPS IS DEMENTED BUT CONSCIOUS
It doesn’t make any difference how beautiful your guess is. It doesn’t make any difference how smart you are.… If it disagrees with experiment, it’s wrong.
—Richard Feynman
CONSCIOUSNESS IS RESILIENT and hard to stamp out. I learned this when I had the good fortune to spend a few years on the neurology wards. What became apparent from talking to and examining patients with various parts of their brains malfunctioning was that consciousness is truly tough to eliminate. Some form of consciousness always persists except when coma or a vegetative state is brought about by extensive cortical damage that leaves the entire brain dysfunctional. Such damage can be the consequence of leaving a helmet behind when it was most needed, a clot or rupture and bleed of a cerebral artery, the surgical removal of a dangerously situated tumor, or a drug overdose. Otherwise, the personality may change, specific abilities may be lost forever, a person’s personal reality may even change, but consciousness keeps coming at you. For sure, the holy grail of science is to find consciousness in the brain, but trust me, it would have been found by now if there were such a thing to find.
Scholars for the past two thousand years of human history have wanted to find the source, the one thing—a spiritual essence, a gland in the forehead, an immortal soul, a brain region—that is responsible for the likes of language, memory, attention, and consciousness. While nobody really knows how any of these capacities we hold so dear actually work, we do know which parts of the brain manage language, memory, and attention. Yet when we try to find the parts of the brain primarily responsible for consciousness, we start to babble, to feel frustrated, because it looks like no such place is to be found. The neurology clinic keeps telling us to try to think about the problem in a different way.
It is always pointed out that there are brainstem lesions that have devastating effects on consciousness, effects so large that people drop into a coma and frequently never come back.* But that is a different kind of thing. If your car was disconnected from its battery, you could never see it work. You couldn’t turn it on and see the things it can do. It’s similar with lesions to the brainstem: the lion’s share of the brain never turns on. There is nothing to observe in extreme cases, and nothing more to understand from them on the topic of consciousness.
Armed with our notions of modules and layers, however, we now can approach the baffling problem of consciousness persisting in the face of various devastating injuries. We have to figure out a way to view how the vast majority of humans behave when the brain is malfunctioning. We have to grasp why consciousness persists.
Overall, the persistence can be attributed to the multitude of modules that continue to contribute to our daily experiences in spite of injury or other malfunctions. Multi-modular brains have at their beck and call a tremendous number of paths to conscious experience. If one route gets destroyed, another may provide an alternate course. To stamp out consciousness, all modules leading to a conscious state must be shut down. Until this happens, intact modules will continue to pass information from one layer to another and induce a subjective feeling of experience. The contents of that conscious experience may be very different from normal, but consciousness remains. Visiting the neuropsychology clinic, we will see how various assaults on our brain affect consciousness and provide insights into how our brains are organized. It turns out that the endless fluctuations of our cognitive life, which are managed by our cortex, ride on a sea of emotional states, which are constantly being adjusted by our subcortical brain.
Visiting the Clinic
The first patient we meet could be anyone’s grandparent. Grandpa shakes my hand in acknowledgment, but he is confused as to who I am. He doesn’t remember meeting me a couple of days before. He suffers from the most common type of dementia, Alzheimer’s disease, which is associated with the production and accumulation of amyloid-β in the brain. That means he has serious neural damage all over the brain. While for the past twenty years or so amyloid has been considered the “cause” of Alzheimer’s, there is recent evidence against that hypothesis, and others are being entertained.1 At any rate, the disease results in the slow destruction of the brain, commencing particularly with the loss of neurons in the entorhinal cortex and the hippocampus, resulting in short-term memory loss. The disease can become so debilitating that it can completely reshape Grandpa’s personality, transforming him from a lively and caring person into a listless shell of his former self. Yet, though he may not recognize me, he is still cognizant of social niceties and shakes my hand. He may wander off, but he will still feel fear when confused and lost, and anger when frustrated. His conscious experience of the world is brought to him through whatever operational neural circuitry continues to function, and as he loses function, it becomes more restricted. The contents of that conscious experience most likely are odd, very different from those of the normal brain or his past self. As a result, odd behavior follows.
The listless version of the formerly jovial grandfather, for example, may still describe himself as his earlier “life of the party” version. Caretakers and family members often attribute a patient’s incongruent self-identity to the disorienting nature of the disease. Yet, when friends and family describe the premorbid personality of a loved one, it is strikingly similar to the self-description provided by the individual in the diseased state.2 This suggests that Grandpa’s false beliefs about his current personality traits are likely due to an inability to update those beliefs. Dementia has left Grandpa with an outdated self-image. As long as Grandpa’s heart continues to beat, consciousness, albeit with a checkerboard of altered contents, will survive the carnage of his degenerating brain.
Our next visit is to a patient known as Mr. B. He has a different kind of problem. He believes he is of special interest to the FBI, which monitors him every single moment of his day. Not only that, the FBI agents film and broadcast his life to the public as The Mr. B Show. Understandably disturbed by this, Mr. B attempts to avoid embarrassing situations by adjusting his behavior. He wears a bathing suit every time he showers, and he changes his clothes under cover of the bedsheets. He avoids social situations, knowing that everyone he encounters is an actor trying to elicit drama to make The Mr. B Show more intriguing. One can barely imagine what it would be like to live in Mr. B’s world. And yet, when carefully analyzed, Mr. B’s case may reveal that a totally rational and normal cortex is trying to make sense out of some abnormalities going on in another region of the brain, the subcortex.
Mr. B suffers from chronic schizophrenia. Risk factors for the disease include a genetic vulnerability and gene-environment interactions. Environmental factors that increase the risk include growing up in urbanized areas,3 being an immigrant,4 especially when socially isolated—such as living in an area with few others of the same group5—and exposure to cannabis.6 No matter what evidence is provided to combat Mr. B’s false beliefs, he is profoundly convinced that he is constantly being viewed by millions of people. A first-rank symptom of schizophrenia is the perception that particular stimuli, ranked unimportant when in a non-delusional state, are extremely and personally significant:7 the guy who glances up from his newspaper is deliberately looking at you; the rock on the road was deliberately placed to harm you. This alteration in salience, that is, what is important and draws one’s attention, is such a classic feature of schizophrenia spectrum disorders that there is a growing movement pushing for the tag “schizophrenia” to be abandoned and the disorder reclassified as a “salience syndrome.”8
A sensory input becomes more salient when the neural signal that it elicits is enhanced over others, which draws attention to it. Shitij Kapur, a psychiatrist, neuroscientist, and professor at King’s College London, distinguishes for us the difference between hallucinations and delusions: “Hallucinations reflect a direct experience of the aberrant salience of internal representations,” whereas delusions (false beliefs) are the result of “a cognitive effort by the patient to make sense of these aberrantly salient experiences.”9 In the brain, the amount of the neurotransmitter dopamine affects the process of salience acquisition and expression. During an acute psychotic state, schizophrenia is associated with an increase in dopamine synthesis, dopamine release, and resting-state synaptic dopamine concentrations.10 Kapur suggests that in psychosis, there is a malfunction in the regulation of dopamine, causing abnormal firing of the dopamine system, leading to the aberrant levels of the neurotransmitter and, thus, aberrant assignment of motivational salience to objects, people, and actions.11 Research supports this claim.12 The altered salience of sensory stimuli results in a conscious experience with very different contents than would normally be there, yet those contents are what constitute Mr. B’s reality and provide the experiences that his cognition must make sense of. When considering the contents of Mr. B’s conscious experience, his hallucinations, his efforts to make sense of his delusions are no longer so wacky, but are possible, though not probable, explanations of what he is experiencing. With this in mind, the behavior that results from his cognitive conclusion seems somewhat more rational. And despite suffering this altered brain function, Mr. B continues to be conscious and aware of his existence.
The Walking Unconscious
Strange behaviors, however, can also arise from a fully intact and functioning brain if only part of it is awake. In a layered brain, lots of activities are happening simultaneously and are coordinated synchronously. What if things get out of sync—if every layer is working, but out of step? Our next visit is to Mr. A, perhaps the most unsettling of our visits.
Mr. A, described by family and friends as a loving family man, was awakened in his bed by his dogs’ barking and strange voices. Racing downstairs, he was met by several police officers with their guns drawn.13 Dazed and confused, Mr. A was cuffed and locked in the back of a squad car, trembling in fear as he tried to assess the situation by listening to the conversations of emergency personnel through the window. He gathered that his wife had been badly hurt and thought that the cops were on the hunt for the person responsible. He didn’t know until later that they had already found their man, and it was he.
In a frazzled panic, Mr. A could only remember falling asleep in his bed a few hours earlier. The police elucidated the tragic situation. Mr. A had brutally murdered his wife during what was later determined to be a sleepwalking episode. During this episode, he had gotten up from bed and gone out to fix the pool’s filter, which his wife had asked him to do at dinner. She must have awoken and gone down to coax him back to bed. His concentration on the motor interrupted, he had turned violent and stabbed her forty-five times, put his tools away in the garage, returned to find her still alive, and rolled her into the pool, where she drowned. Then he returned to bed. His neighbor, hearing screaming and barking next door, looked over the fence to see a “bewildered”-appearing Mr. A roll a body into the pool, and called the police.
The idea that someone could kill his wife, whom he loved, while sleepwalking is unfathomable. Yet, with no identifiable motive, no attempt to hide the body or weapon, and no memory of the event, the jury was convinced that his actions occurred unintentionally and out of Mr. A’s awareness. If this is true, what exactly went on in Mr. A’s mind and brain during this atrocity?
Sleepwalking is a parasomnia, a strange behavior that occurs during sleep. Over the years, sleep experts have identified two main stages of sleep by recording brain waves—rapid eye movement (REM) and non–rapid eye movement (non-REM) sleep. Sleepwalking usually occurs after an abrupt and incomplete spontaneous arousal from the non-REM sleep that occurs in the first couple of hours of the night, turning one into a mobile sleeper. Trying to waken sleepwalkers is fruitless and can be dangerous, since the sleepwalker may feel threatened by physical contact and respond violently. Normally, non-REM sleep shifts into REM sleep, during which there is a loss of muscle tone, preventing motor behavior during REM sleep. The majority of sleepwalking episodes tend to be relatively harmless and usually make for a good story as told by the witness, often beginning with “You won’t believe what you did last night!” And if you are the sleepwalker you don’t believe it, because you will have no memory of your midnight shenanigans.
Most parasomniac behaviors appear irrational and are disconcerting to watch. The sleepwalker may start vacuuming or sweeping the patio in the middle of the night, oblivious to surroundings. In rare instances, sleepwalkers engage in very complex and potentially dangerous activities, such as mowing the lawn, repairing a motorcycle, or driving a car. Complex behaviors such as these make it difficult to believe that the sleepwalker is not consciously aware of his or her actions in the moment. Rarely, these complex behaviors turn violent. When the law is involved, whether the behavior was intentional or not becomes key, thus intensifying the debate over whether or not these people are conscious during their sleepwalking activities.
A clearer picture of what is happening in the brain during non-REM sleep,14 during sleepwalking,15 and during confused arousals16 has been achieved through neuroimaging and EEG. It appears that the brain is half awake and half asleep: the cerebellum and brainstem are active, while the cerebrum and cerebral cortex have minimal activity. The pathways involved with control of complex motor behavior and emotion generation are buzzing, while those pathways projecting to the frontal lobe, involved in planning, attention, judgment, emotional face recognition, and emotional regulation are zoned out. Sleepwalkers don’t remember their escapades, nor can they be awakened by noise or shouts, because the parts of the cortex that contribute to sensory processing and the formation of new memories are snoozing, temporarily turned off, disconnected, and not contributing any input to the flow of consciousness.
It is likely that Mr. A consciously experienced aspects of the episode, but very differently than his awake self would have. With a layered brain in mind, we can predict that certain “lower-level” consciousness-producing modules were active, allowing him to adeptly navigate and coordinate movements and feel emotions, while other, “higher-level” ones remained asleep and silent, preventing him from comprehending the situation, recognizing his wife, hearing her screams, or remembering the event. System-wide, particular regions were isolated and disconnected, and only certain modules were contributing to his behavior and his conscious experience. Unfortunately, the cortex was asleep, locked up tight and contributing nothing. When Mr. A snapped out of his sleep cycle, these silent modules awoke to a nightmarish reality. During this horrendous incident the awake regions of his undamaged brain, unfettered by the processing of the cognitive control modules of his sleeping cortex, produced behavior that markedly strayed from that of this normally compassionate, nonviolent man. The fact that these actions completely went against Mr. A’s personality traits and ideals is exactly why jurors settled on a “not guilty” verdict.
Unmoving but Conscious
In contrast, one of the most nightmare-inducing brain injuries is a lesion to the ventral part of the pons in the brainstem. The loss of these neurons, which connect the cerebellum with the cortex, leave one unable to move but fully conscious. This famously happened to Jean-Dominique Bauby, the editor in chief of the French Elle magazine, when he suffered a stroke at the age of forty-three. Waking up several weeks later from a coma, fully conscious and with no cognitive loss, he was unable to move anything except his left eyelid.17 That also meant he couldn’t talk, and thus couldn’t tell anyone that he was conscious. He had to wait until someone noticed that he appeared to voluntarily blink his eyelid. This is known as “locked-in” syndrome. The lucky ones, if you can call it that, can voluntarily blink or move their eyes, though the movement is small and tiring. This is how they communicate. The unlucky ones cannot.
In many cases, it has taken months or years before it was recognized by a caregiver that the patient was conscious, suffering medical procedures without anesthesia and hearing conversations about his own fate that he could not participate in. Once it was recognized that Bauby was conscious, he took advantage of his ability to blink his eye. He wrote a book describing his conscious experience as he lay paralyzed. He would construct and memorize sentences as he lay there. Then, for four hours a day, an amanuensis patiently sat at his bedside going through a frequency-ordered French alphabet, and Bauby would blink when the correct letter was spoken. Two hundred thousand blinks later, The Diving Bell and the Butterfly was done. In the prologue, speaking in the third person, he describes the condition he awoke to find himself in: “Paralyzed from head to toe, the patient, his mind intact, is imprisoned inside his own body, unable to speak or move. In my case, blinking my left eyelid is my only means of communication.”18 He describes feeling stiff and being able to feel pain, yet he goes on to say,
My mind takes flight like a butterfly. There is so much to do. You can wander off in space or in time, set out for Tierra del Fuego or for King Midas’s court.
You can visit the woman you love, slide down beside her and stroke her still-sleeping face. You can build castles in Spain, steal the Golden Fleece, discover Atlantis, realize your childhood dreams and adult ambitions.19
Bauby is an example of the endless capacity of human adaptability. In fact, adaptability appears to be de rigueur for such patients, for 75 percent have rarely or never had suicidal thoughts.20 Even with this devastating injury to part of the brainstem, consciousness remains, accompanied by the full range of feelings about both present and past experiences.
When modules and layers are damaged or malfunctioning, strange behaviors can result. From the widespread cortical damage and disruption in Alzheimer’s disease to the specific disorders of brainstem damage, a picture begins to emerge: it takes an understanding of both the cortex and the subcortex to capture the ever-changing moments of conscious experience. Could it be that all of those fleeting conscious thoughts occur on a bed of a few specific emotional states that give those thoughts a subjective feel? Could it be this all fits into the brain’s layered architecture, with the evolutionarily older brain system—still wired up to signal the organism to fight or run, or to seek mates or to eat—operating outside the direct control of the cognitive layers? Is the layered-architecture model going to give us the means to comprehend how we are organized to be conscious?
Subcortical Emotional Feelings Engine
A long-standing belief is that the cerebral cortex is responsible for all forms of consciousness, and that without it we would be not just unconscious but with no capacity to be conscious at any level, that is, a conscious-less being in a vegetative state.21 The cortex, however, could simply be a collection of extensions (apps!) to enhance conscious experiences. Sure, it provides us with several dynamic mental skill sets—that is, ones that can change and are constantly active—but it might not be essential for giving us a raw subjective feeling. Underneath the cortical hood are several subcortical networks that are essential for maintaining consciousness. It is lesions to these subcortical regions that can result in a coma, where a person or animal becomes nonresponsive and appears unconscious to an outside observer.22 Even a fully functional cerebral cortex cannot salvage the wreckage of some types of subcortical damage.
The challenge of drawing the line between a conscious and an unconscious state has, in the past, largely been semantic. The term “consciousness” lacks objectivity because it is difficult to define a subjective feeling of existence. This is the main reason why the defining features of consciousness are hotly debated. As soon as one steps into the clinic, however, identifying conscious states is of the utmost urgency, and is no longer simply a semantic problem but an ethical one, too. Denying pain medication to a seemingly unconscious patient who, unbeknownst to you, is conscious is torture. Despite the ambiguity surrounding the term, there is compelling evidence to suggest that the cerebral cortex is not neces-sary to evoke some forms of consciousness. The capabilities of subcortical systems appear competent enough on their own to provide a subjective feeling.
That evidence comes from the pediatric clinic. Sadly, some children are born with anencephaly (without a cerebral cortex due to genetic or developmental causes) or hydranencephaly (very minimal cerebral cortex, often the result of fetal trauma or disease). The neuroscientist Björn Merker became interested in the subcortex early in his career. Frustrated by the limited information on and few case studies of children with hydranencephaly, he joined a worldwide Internet group of parents and caretakers of these children to learn more about them and their condition. He came to know several families and spent a week with them at Disney World. Over the course of that week he observed that the children “are not only awake and often alert, but show responsiveness to their surroundings in the form of emotional or orienting reactions to environmental events.… They express pleasure by smiling and laughter, and aversion by ‘fussing,’ arching of the back and crying (in many gradations), their faces being animated by these emotional states. A familiar adult can employ this responsiveness to build up play sequences predictably progressing from smiling, through giggling, to laughter and great excitement on the part of the child.”23 Without a cerebral cortex or the cognition it supplies, these children were feeling emotions, having a subjective experience, and were conscious. No one would mistake them for a child with a cerebral cortex, but they are aware and their emotional response to stimuli is appropriate.
Over the years, Merker has reached the conclusion that it is the midbrain that supports the basic capacity for conscious subjective experience. Sure, the cortex elaborates on the contents of the experience, but the capacity itself arises from the midbrain structures. The ethical implications of this are obvious. Merker notes that parents often encounter medical professionals who are surprised when asked for pain medication for these children when they are to undergo invasive procedures.
The main argument opposing the idea that these children are experiencing the world through their subcortical structures is drawn from the fact that almost all of them have some portions of their cerebral cortex spared. Yet although the very limited intact cortical regions (of questionable functionality) vary widely from child to child, their behavior is fairly consistent, and it is asymmetrical with the tissue that is present. For example, while the auditory cortical tissue is rarely preserved, hearing is usually preserved, and while it is common for some visual cortex to be preserved, vision tends to be compromised.
Merker’s theory is bolstered by research into the emotional life of animals. The Estonian-born neuroscientist Jaak Panksepp studied the nature of emotions in animals for half a century. He differentiated two types of consciousness: the evolutionarily old affective consciousness (conscious of raw emotional feelings) and the relative newcomer, cognitive consciousness (which allows one to think about those emotional feelings). In a lecture, he told the story about the final lab practicum he gave to his undergraduates at the end of the course. He would prepare two rats for each student to study. One of the rats was decorticated, leaving only subcortical tissue. The other rat was given a sham operation, which means it underwent surgery, but nothing was actually removed from the brain. The students were to study their pair of rats for two hours on a wide range of tasks that they had learned about in the class. When time was up, they had to guess which rat had lost all of its cerebral cortex and explain their choice. Twelve of the sixteen class members declared the decorticated rats were the neurologically normal ones!
What the students observed in these rats was motivated behavior, such as searching for food, mating, fighting or escaping when attacked, and wrestling playfully with other rats.24 To those students, the behavior that they observed was ratty enough to declare them normal! If the cortex is solely responsible for mediating consciousness, then removal of the cortex should have caused those rats to be unresponsive to other playful rats and everything else. Yet removing their cortex did not stamp out their basic competences and responses, meaning that the upper brainstem mechanisms were enough to sustain many of their behaviors, including their emotional and motivational feelings, discussed below.
Feelings Tie to Consciousness
These studies of decorticated rats and children with hydranencephaly suggest that subcortical structures can transform raw neural input into something resembling core emotional feelings. Subcortical brain areas have their own dynamics, arose early in the evolutionary process, and are anatomically, neurochemically, and functionally homologous in all mammals that have been studied.25 Panksepp argued that we share these brain areas that produce the emotions we feel with other animals, and these areas have been selected for their ability to enhance survival. How? The emotions act as an interior reward and punishment system that informs an animal how it is faring in the quest for survival. Positive emotional feelings egg the animal on, while negative feelings, depending on their strength, indicate anything from iffy to disastrous situations. Thus, these internal senses provide a way to assess the external environment and are powerful drivers of behavior, despite their relative simplicity at the level of consciousness.
The Caltech researchers David Anderson and Ralph Adolphs are on the same page as Panksepp.26 They argue that an emotion is an unconscious central nervous system state that is triggered by a specific stimulus, whether it be external, such as a predator, or internal, such as the memory of one. When activated, the neural circuit that encodes this state causes multiple parallel processes to kick into gear, which produce a behavioral response, feelings, cognitive changes, and somatic responses, such as a racing heart and a dry mouth. One can feel without cognition kicking in and reporting that feeling.
According to Panksepp, seven primal emotional and motivational feelings that appear to be common features of animal and human consciousness at both a behavioral and a neural level are SEEKING, FEAR, RAGE, LUST, CARE, GRIEF, and PLAY. These feelings, which can largely be attributed to functions of the subcortical limbic system, drive animals to behave in ways that promote finding food, shelter, and mates; avoiding harm; protecting oneself and kin; and building relationships with friends and family. If we consider consciousness to be a subjective feeling about something, then we must consider emotions to be a foundational component of consciousness.
Panksepp concluded that emotional feelings were such a successful tool for living that they were coded into the genome in rough form, have been conserved across all mammals, and only later in the evolutionary process were they gilded with learning mechanisms and higher-order cognitions provided by an add-on extension: the cortex.27 If these feelings existed before cortical tissues, then the special wiring of these subcortical networks alone must possess what is necessary to produce the feelings that accompany conscious experience. By understanding the layered system of subcortical networks, we can, perhaps, better appreciate the most primitive form of consciousness. The emotional and motivational feelings and the behaviors they produce in animals can teach us a lot about how modular systems promote consciousness and perhaps indicate what aspects of human consciousness are unique.28
New York University’s Joseph LeDoux, who has painstakingly elucidated what he formerly referred to as the fear circuits and now calls threat circuits, has a different take. He has two major concerns. The first is that there still is no agreed-upon definition of emotion; the second is that there are those who challenge the notion that there are common basic emotions. Thus, how can one confidently differentiate emotion from other psychological states or compare emotions across species? LeDoux writes: “The short answer is that we fake it. Introspections from personal subjective experiences tell us that some mental states have a certain ‘feeling’ associated with them and others do not.” This leads him to worry about claims that similar behavior in animals indicates a similarity of experience.29 From his perspective, the cortex is necessary for affective feelings. He thinks that subcortical circuits produce emotional behavior and physiological responses, but that they only indirectly contribute to subjective feelings. He requires an additional cognitive step for the production of subjective feelings, which is provided by higher cortical circuits that read out and interpret the emotional behavior. He is not alone in holding this view. In fact, the majority of emotion researchers would give such cognitive “readout” theories the thumbs-up. LeDoux suggests that conscious feelings are a two-step process and result when a physiological response is read out by the parts of the prefrontal cortex that support working memory.
While this battle over emotions is fought, we can remain on the sidelines because a layered brain architecture can accommodate either scenario. What is important is that both the subcortex and the cortex contribute to the full conscious experience. From one perspective, the children with hydranencephaly have emotional feelings that appear identical to those of children with intact cortices. Because their overt behavior is similar, we quickly map the full complement of a meta-self-aware (aware that they are aware) conscious experience onto them. Are they self-aware? Without a cortex supplying the necessary functions for cognition, they are unable to know they are self-aware. At a minimum, for a full-blown awareness that you are having a conscious experience, both layers must be functioning.
Consciousness Enhanced by the Cortex
Is the cortex overrated if subcortical circuitry contains the essential ingredients for consciousness? Mais non! The point is that the subcortex should not be underrated. By understanding the contribution of subcortical processing to consciousness, we are better equipped to realize why it is so hard to get rid of this incessant feeling of feelings. The cerebral cortex clearly plays the role of providing the contents of consciousness, given how brain damage to that area often coincides with specific behavioral changes. What exactly is the role of the cerebral cortex in producing consciousness? The cortex expands the number of ways in which we can experience the world, which allows for a vast variety of possible conscious experiences and responses.
The particular brand of cortex that each species possesses provides it with its own particular contents of conscious experience. Part of the contents of human consciousness is language. Only humans have come up with nifty little symbols that, in a specific combination, can give another person a specific mental representation of some abstract idea. Not only do we have the capacity to learn language, but we are also biologically prepared for language acquisition.30 As we discussed in chapter 4, we have entire brain regions dedicated to various aspects of learning, comprehending, and producing language. Another trip to the clinic will show us that damage to one region will destroy our ability to comprehend words, but leave us able to produce grammatically correct nonsensical sentences with proper prosody and intonation. Lesions in a different area will have us comprehending sentences but unable to construct them. Lesions in another area, and you will be unable to say nouns but still be capable of recognizing and comprehending them. Any such damage will result in a different conscious experience, but none will destroy consciousness itself.
While language adds to our conscious experiences, we would still be conscious without it, though many of our experiences would be markedly different. Consider the life of the French feral child Victor of Aveyron, immortalized in François Truffaut’s 1970 film L’Enfant Sauvage. Found at age twelve, Victor had spent his childhood alone in the woods, never having been exposed to language, and had never learned to speak. He was definitely conscious and having conscious experiences, yet with contents different from what they would have been had he learned to speak. When the functionality of one module does not develop, other modules step in to give you an alternative experience.
There is a lot of debate about whether subcortical structures are the main driving force of consciousness31 or whether consciousness is primarily mediated by the cerebral cortex.32 When thinking about brain functioning, however, there may not be a specific modular hierarchy that allows consciousness to manifest itself in one way or another. Specific modules work relatively independently and, rather than being a neatly ordered queue of modular processing, the contents of our conscious experience may be the result of some kind of competition: some processing takes hold of your conscious landscape at a given moment in time, and some doesn’t. In this view, both subcortical and cortical modules have the capacity to produce a form of conscious experience that does not necessarily require intervention from “lower” or “higher” cognitive systems. Rather, the multitude of conscious-producing modules simply diversifies your conscious portfolio. To better illustrate this concept, let’s try to stamp out consciousness with an iron rod.
One of the most fascinating and famous brain lesions in history arose from a railway construction explosion that sent a searing hot metal rod through the skull and left frontal lobe of a construction worker named Phineas Gage. Surprisingly, Phineas did not appear to lose consciousness even moments after the accident! Personally, I’d rather have experienced Muhammad Ali’s anchor punch that knocked out Sonny Liston than have an iron rod bust open my cranium, but apparently Ali’s punch more effectively stamped out consciousness (at least momentarily). Although Sonny recovered from Ali’s punch, immediate and permanent brain damage ensued for Phineas Gage. Despite missing half of his frontal lobe, Phineas could still function similarly to the way he did before his accident. His actual manners drastically changed, however, as the once professional and respectful Phineas became a lewd, disrespectful man.33 Phineas became less conscientious in his actions toward others, but he did not become any less conscious. His range of possible conscious experiences diminished a bit, as it seemed his once sympathetic attitudes toward colleagues were replaced with experiences of agitation and aggression. Phineas Gage suffered from what is now called frontal lobe syndrome, in which he lost all functionality of his left frontal lobe. When frontal lobe damage occurs, people tend to have difficulty regulating their emotions.34 This loss of emotional control might be attributed to the subcortical modules “winning” the competition to provide an overarching conscious experience more often, since there is less competition from modulating frontal tissues. Regardless of the underlying reason for loss of emotional control in frontal lobe syndrome, one fact remains consistent across all cases: the person is still conscious.
There are a tremendous number of brain lesion cases that paint a similar picture: Damage or dysfunction in brain region X causes a change in behavior Y, but consciousness almost always remains intact. The modular brain makes consciousness resilient because of the plethora of possible paths that can lead to a conscious moment. Only a brain organized in this way can explain these facts of neurology. Losing modules causes losses in specific functionalities, but the mind keeps on producing a continuous conscious stream as if nothing changed. The only thing that has changed is the contents of that stream. Not only does this provide evidence that the brain operates in a modular fashion, but it also suggests that independent modules can each produce a unique form of consciousness.
The Ubiquity of Consciousness
What we have learned from visiting the neurology clinic is that severe brain damage across various locations of the brain cannot stamp out consciousness per se. Certain contents of conscious experience may be lost, but not consciousness itself. This fact suggests that there is not a specific “Grand Central” cortical circuit that produces consciousness, but that any part of the cortex can produce it when supported by subcortical processing, and that subcortical processing alone can support a limited type of conscious experience. Thus, it appears that it is the processing of local modular circuits that provides the contents of conscious experience.
Although these modular systems are largely independent, communication between modules helps coordinate the flow of consciousness. This communication is important to keep each module up-to-date on recent personal events. Just as the news informs citizens of worldly events as they occur, the connections between modules coordinate information to make sure all modules are functioning on the same page. We only notice when communication is a day late and a dollar short. Rustling noises outside the back door at night may activate the subcortical fight-or-flight response, and you grab your phone to call the police, only to realize in the next moment when cognition kicks in that it is a raccoon going through your trash, again. Thank your limbic system for quickly getting you prepared for a potentially dangerous situation, but there is no danger here, just another mess to deal with in the morning.
This incessant interplay between cognition and feelings, which is to say between cortical and subcortical modules, produces what we call consciousness. There obviously is a different feel to a wave of intense emotion versus an abstract thought, but each conscious form is an experience that gives us a unique perception of reality. The pattern in which these various conscious forms come in and out of awareness gives us our own personal life story. The vast variety of conscious forms and the ubiquity of consciousness in the brain are best explained by a modular architecture of the brain. The conceptual challenge now is to understand how hundreds, if not thousands, of modules, embedded in a layered architecture—each layer of which can produce a form of consciousness—give us a single, unified life experience at any given moment that seems to flow flawlessly into the next across time. The key idea, as we shall see in chapter 9, is time. It is the unending sequence of modules having their moment.
How that works is coming up, but before getting to it, we have to deal with the elephant in the room. Whatever model one has for how the brain does its trick of turning neuronal firings into mental events, we must try to understand the gap between those two phenomena, one objective (neuronal) and the other subjective (mental), and whether bridging that gap is even possible. No matter whether you think that local modules are responsible or that central brain circuits underlie what we call conscious states, you still have to deal with the gap. Some feel this is an impossible assignment.
To get at this fundamental question, we’re going to have to look back at what the mathematicians and physicists have been thinking about for the past 150 years. After all, their lot came up with perhaps the greatest ideas in human history, the theory of relativity and quantum theory. Their thinking was truly on the edge of human mental capacity, and they were grappling with phenomenal unknowns. The fruits of their thinking were virtually ignored by biologists, psychologists, and neuroscientists and dismissed as irrelevant to the problem of consciousness. I think they can help, because what has gone underappreciated from math and physics is the idea of complementarity, which holds that a single thing can have two kinds of description and reality. Could that idea help us with the deep divide between the mind and brain? Could it help us understand the “explanatory gap” between the reality of the physical world—that material brain of ours made up of chemicals governed by the laws of physics—and the reality of that seemingly nonmaterial subjective experience? I think it can, and before we get ahead of ourselves, let’s familiarize ourselves with the physics that may yet hold the key.