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.