Hustvedt: Most of us with any ability for introspection are aware that there are layers of experience. Take fiction-writing. You sit down, and on the page there appears a world that emerges from somewhere—a mental geography that is mostly unconscious. But making art also depends on our capacity for symbolization.

Damasio: Those separate layers and multiple worlds depend on diverse performance spaces in the brain and on sophisticated brain mechanisms of integration. They also depend on memories being formed of one’s integrated experiences and being recalled later. Right now I can see the pearls around your neck, your deep-pink sweater and white blouse, and your beautiful blond hair. At the same time I am hearing your voice and processing certain ideas about you and about what you and I are saying. All of these processes occur in different places in my brain, but timing and the fact that we have a single self will give me a unified experience of time and space.

How do I make a memory of this moment? We need to find systems in the brain where signals related to all these different things can converge (video) and code for the simultaneity of events . Later, converging signals can be reactivated and sent back to the regions they came from, reconstructing a paler version of the original experience. I believe this is how memory works. When we hear a tune in our mind and recall the people we were with and the place where we last heard it, we are using this convergence-divergence framework to reconstruct the fragments that composed the original set.

This framework is quite economical. Instead of having to record every event that you go through every day with every person, the books you read, the things you see and hear and touch and smell, all you need to do is record conjunctions of aspects of events. If tomorrow I remember talking to you today, I will reconstruct some aspects of our session, and this recall will relate to the original, of course. But I will not reproduce a facsimile memory of the session. I will put together bits and pieces of this experience, and they will reconstruct parts of this moment, but the reconstruction will not be entirely accurate. In time I may even make a confused recall and say that you were wearing a blue sweater.

Hustvedt: Our brains and our memories are not like recording devices, not like film, and that is why we can sometimes make significant errors. Those errors can be created by the emotion attached to an experience. You can even invert a memory—create its opposite—depending on your motivation. I don’t mean conscious motivation, but a deeply embodied drive or push that has a powerful emotional valence, which then alters the memory. Emotion also consolidates memories. We remember things that meant something to us and forget what we were indifferent to.

Damasio: When people testify in court, they make all sorts of errors and inversions of time sequences because memory is not like a filmic medium. Our brains don’t use celluloid with an optic sound track attached to it. What we have is this incredibly sophisticated mechanism of coding. By the way: We do not have memory only of the things that we have been living through since we were born. We also have past memories that we have inherited through the whole history of evolution before us. We have memories of things our forerunners did, and I’m not just talking about the human forerunners, but forerunners that go all the way back to reptiles and single cells.

Hustvedt: How does consciousness fit into this?

Damasio: My perspective on consciousness has changed a lot. I used to think of consciousness as a late evolutionary development, a property that gave access to higher thinking and reasoning and tended to be largely human, although not exclusively. But now I see consciousness as something that is widely available in many other species—in all mammals and birds and reptiles, for example. The forerunners of consciousness can be found in the processes of managing life that are present in very simple life-forms. Take the example of bacterial cells, which can even organize socially. Without a brain or a nervous system of any kind, bacteria can sense how many of them are there in a group—something called quorum-sensing—and decide to attack or not based on the collective messages they pool. In a way, they are answering, by dint of their behavior, an unposed and complicated question such as “Do we have enough troops to fight for this territory?”

Hustvedt: Bacteria have drives, but they don’t have reflective self-consciousness. They can’t “see” themselves doing what they’re doing while they’re doing it. They can’t imagine what tomorrow will be like or explicitly report on what they were up to last week. Human beings have projective abilities, and this capacity to project the self in time—into both the past and the future—is the core of the imagination. The imaginary realm cannot be cut off from its neurobiological roots, but without it we would have no culture.

Damasio: With our complex brains we have evolved the ability to project the process of consciousness into a completely different dimension.

Hustvedt: The French phenomenologist Maurice Merleau-Ponty argued for an embodied intentionality that was far more than a self-conscious “aboutness.” It is lodged in biological processes but extends up and out into our ability to recognize ourselves in the mirror, to imagine ourselves as other people, to entertain fantasies about the future, to create fiction and art. Unconscious processes or drives lie beneath all conscious processes. Dogs, cats, even snails are conscious—awake and aware and remembering—but they don’t recognize themselves in mirrors and don’t imagine themselves from other perspectives. They can’t pretend. Pretending seems to be an exclusively human ability.

Damasio: As conscious individuals we can invent something new. I call the process “sociocultural homeostasis” because it targets a problem in the complex system—in this case, society—so the system operates as efficiently as possible. This is the case with moral rules and laws, which aim at curbing dangerous behaviors that compromise the function of individuals and of the group. Religion and the arts are restorative endeavors that accomplish homeostasis by promoting a smoother functioning of individuals and groups.

Next page: The 12 Steps to Consciousness

The 12 Steps to Consciousness

“We take consciousness for granted because it is so available, so easy to use, so elegant in its daily disappearing and reappearing acts, and yet, when we think of it, we do puzzle. What is consciousness made of? Mind with a twist, it seems to me, since we cannot be conscious without having a mind to be conscious of. But what is mind made of? Does mind come from the air or from the body?” Damasio poses these eternal questions in his new book, Self Comes to Mind, and serves up some answers below.

1 THE MIND IN THE BRAIN  Organisms make minds out of the activity of special cells known as neurons. Neurons are sensitive to changes around them; they are excitable (an interesting property they share with muscle cells). Thanks to a fibrous prolongation known as the axon, and to the end region of the axon known as the synapse, neurons can send signals to other cells, often quite far away. The number of neurons in each human brain is on the order of billions, and the synaptic contacts that the neurons make among themselves number in the trillions. Neurons are organized in small microscopic circuits, whose combination constitutes progressively larger circuits, which in turn form networks or systems. Minds emerge when the activity of small circuits is organized across large networks so as to compose momentary patterns.

2 THE CONSCIOUS SYM­PHONY  Conscious minds result from the smoothly articulated operation of several, often many, brain sites. The ultimate consciousness product occurs from those numerous brain sites at the same time and not in one site in particular, much as the performance of a symphonic piece does not come from the work of a single musician or even from a whole section of an orchestra. The oddest thing about the upper reaches of a consciousness performance is the conspicuous absence of a conductor before the performance begins, although as the performance unfolds, a conductor comes into being. For all intents and purposes, a conductor is now leading the orchestra, although the performance has created the conductor—the self—not the other way around. Building a mind capable of encompassing one’s lived past and anticipated future, along with the lives of others added to the fabric and a capacity for reflection to boot, resembles the execution of a symphony of Mahlerian proportions. But the true marvel is that the score and the conductor become reality only as life unfolds. The grand symphonic piece that is consciousness encompasses the foundational contributions of the brain stem, forever hitched to the body, and the wider-than-the-sky imagery created in the cooperation of cerebral cortex and subcortical structures, all harmoniously stitched together, in ceaseless forward motion, interruptible only by sleep, anesthesia, brain dysfunction, or death.

3 MIND MAPS  The patterns, or maps, of the mind represent things or events outside the brain, either in the body or in the external world. Ultimately, consciousness allows us to experience maps as images, to manipulate those images, and to apply reasoning to them. Maps are constructed when we interact with objects, such as a person, a machine, or a place, from the outside of the brain toward its interior. Maps are also constructed when we recall objects from inside our brain’s memory banks. The construction of maps never stops, even in our sleep. The human brain maps whatever object sits outside it, whatever action occurs outside it, and all the relationships that objects and actions assume in time and space, relative to each other and to the mother ship known as the organism. The human brain is a mimic of the irrepressible variety.

4 THE BEGINNING OF CONSCIOUSNESS  Imagine holding a brain in your hand and looking at the surface of the cerebral cortex. Now imagine taking a sharp knife and making cuts parallel to the surface, at a depth of two or three millimeters, and extracting a thin fillet of brain. After fixing and staining the neurons with an appropriate chemical, you can lay your preparation down on a thin glass slide and look at it under the microscope. You will discover, in each cortical layer that you inspect, a sheathlike structure that essentially resembles a two-dimensional square grid. The main elements in the grid are neurons, displayed horizontally. You can imagine something like the plan of Manhattan. Contemplating a patch of cerebral cortex, one realizes why the idea of brain maps is not a far-fetched metaphor. One can sketch patterns onto such a grid, and when one squints a little and lets the imagination roam free, one can picture the sort of parchment paper that Henry the Navigator probably pored over when he was planning the voyages of his captains. One big difference is that the lines in a brain map are not drawn with quill or pencil; they are, rather, the result of the momentary activity of some neurons and of the inactivity of others.

5 CONSCIOUSNESS IN MOTION  Brain maps are not static like those of classical cartography. Brain maps are mercurial, changing from moment to moment to reflect the changes that are happening in the neurons that feed them, which in turn reflect changes in the interior of our body and in the world around us. The changes in brain maps also reflect the fact that we ourselves are in constant motion. We come close to objects or move away from them; we can touch them and then not; we can taste a wine, but then the taste goes away; we hear music, but then it comes to an end; our own body changes with different emotions, and different feelings ensue. The corresponding brain maps change accordingly. A spectacular consequence of the brain’s incessant and dynamic mapping is the mind. The mapped patterns constitute what we, conscious creatures, have come to know as sights, sounds, touches, smells, tastes, pains, pleasures, and the like—in brief, images. The images in our minds are the brain’s momentary maps of everything and of anything, inside our body and around it, concrete as well as abstract, actual or previously recorded in memory. Perception, in whatever sensory modality, is the result of the brain’s cartographic skill.

6 THE BODY IN THE MIND  Because brain maps are the substrate of mental images, mapmaking brains have the power of literally introducing the body as content into the mind. But body-to-brain mapping has a peculiar aspect: Although the body is the thing mapped, it never loses contact with the mapping entity, the brain. Under normal circumstances they are hitched to each other from birth to death. Just as important, the mapped images of the body have a way of permanently influencing the very body they originate in. Any theory of consciousness that does not incorporate these facts is doomed to fail.

7 SENSUAL WINDOWS ON THE WORLD  The brain’s pervasive, exhaustive mapping of the body covers not only what we usually regard as the body proper—the musculoskeletal system, the internal organs, the internal milieu—but also the body’s spying outposts—the smell and taste mucosae, the tactile elements of the skin, the ears, the eyes. Those devices have a part made of “old flesh” and another made of delicate and special “neural probes.” Examples include the cochlea in the inner ear, with its sophisticated hair cells and sound-mapping capabilities, and the retina at the back of the eyeball, onto which optical images are projected. The combination of old flesh and neural probe constitutes a body border. Because of this curious arrangement, the representation of the world external to the body can come into the brain only via the body itself. The body and the surrounding environment interact with each other, and the changes caused in the body by that interaction are mapped in the brain. Body-brain communication goes both ways, from body to brain and in reverse. The body tells the brain: This is how I am built and this is how you should see me now. The brain tells the body what to do to maintain its even keel.

8 FEEL THAT EMOTION  Emotions are complex, largely automated programs of actions concocted by evolution. The actions are carried out in our bodies, from facial expressions and postures to changes in viscera and internal milieu. Feelings of emotion, on the other hand, are composite perceptions of what happens in our body and mind when we are emoting. As far as the body is concerned, feelings are images of actions rather than actions themselves. While emotions are actions accompanied by ideas and certain modes of thinking, emotional feelings are mostly perceptions of what our bodies do during the emoting, along with perceptions of our state of mind during that same period of time.

9 CONSCIOUSNESS OBSERVED  Consciousness is a state of mind—if there is no mind there is no consciousness. The conscious state of mind is experienced in the exclusive, first-person perspective of each of our organisms, never observable by anyone else. We can amplify this definition by saying that conscious mind states always have content: They are always about something. Finally, conscious states of mind are possible only when we are awake. Conscious states of mind are felt.

10 THE AUTOBIOGRAPHICAL SELF  Autobiographies are made of personal memories, the sum total of our life experiences, including the experiences of the plans we have made for the future, specific or vague. Autobiographical selves are autobiographies made conscious. They draw on the entire compass of our memorized history, recent as well as remote. The social experiences of which we were a part (or wish we were) are included in that history, and so are memories that describe the most refined among our emotional experiences, namely, those that might qualify as spiritual. As lived experiences are reconstructed and replayed, their substance is reassessed and inevitably rearranged, modified minimally or very much in terms of their factual composition and emotional accompaniment. Entities and events acquire new emotional weights during this process. Some frames of the recollection are dropped on the mind’s cutting-room floor, others are restored and enhanced, and others still are so deftly combined either by our wants or by the vagaries of chance that they create new scenes that were never shot. Given the abundance of records of one’s lived past and anticipated future, we do not need to recall all of them or even most of them to operate in autobiographical mode. Not even Proust would have needed to draw on all of his richly detailed and long-ago past to construct a moment of full-fledged self-Proustiness.

11 THE REFLECTIVE SELF  Systematic discovery of the drama of human existence and its compensations was arguably possible only after the development of full human consciousness—a mind with an autobiographical self that is capable of guiding reflective deliberation and gathering knowledge. Eventually, given the probable intellectual capability of early humans, it is likely that they would have wondered about their status in the universe, something akin to the “where from” and “where to” questions that still haunt us today. That is when the rebellious self comes of age. That is when myths are developed, when social conventions and rules are elaborated, leading to the beginnings of a true morality. I suggest that the engine behind these cultural developments is the homeostatic impulse—the dynamic process by which the brain regulates life. In one form or another, cultural developments respond to detection of an imbalance in the life process, and they seek to correct it.

12 WHY CONSCIOUSNESS PREVAILED  Traits and functions rise or fall in the history of life depending on how much they contribute to the success of living organisms. The most direct way of explaining why consciousness has prevailed in evolution is to say that it has contributed significantly to the survival of the species so equipped. Consciousness has flourished. It seems to be here to stay. What did it actually contribute? The answer is a large variety of apparent and not-so-apparent advantages in the management of life. Even at the simplest levels, consciousness helps the optimization of responses to environmental conditions. As processed in the conscious mind, images provide details about the environment, and those details can be used to increase the precision of a much-needed response, for example, the exact movement that will neutralize a threat or guarantee the capture of prey. But the lion’s share of the advantage comes from the fact that the conscious mind infuses the exploration of the world outside the brain with a concern for the first and foremost problem facing the organism: the successful regulation of life.