The big C

18/01/2010 by admin.

Here is an interesting take on consciousness. It is the C in an AtoZ by P. Long in My Brain on My Mind. (here)

Consciousness, according to neuroscientists Francis Crick and Christof Koch, is “attention times working memory.” “Working memory” being the type of memory that holds online whatever you are attending to right now. Add to “attention times working memory” a third element of consciousness—the sense of self, the sense of “I” as distinct from the object of perception. If I am conscious of something, I “know” it. I am “aware” of it. As neurobiologist António Damásio puts it in The Feeling of What Happens, “Consciousness goes beyond being awake and attentive: it requires an inner sense of the self in the act of knowing.” (It also requires the neurotransmitter acetylcholine.)

There is another theory of consciousness, the quantum physics theory of consciousness, in which quarks, a fundamental particle, have proto­consciousness. This theory is said to have an aggregation problem—how would zillions of protoconscious particles make a conscious being? It puts consciousness outside life forms and into moonrocks and spoons. I will leave that theory right here.

In dreamless sleep, we are not conscious. Under anesthesia, we are not conscious. Walking down the street in a daze, we are barely conscious. Consciousness may involve what neuroscientist Jean-Pierre Changeux postulates is a “global workspace”—a metaphorical space of thought, feeling, and attention. He thinks it’s created by the firing of batches of neurons originating in the brain stem whose extra-long axons fan up and down the brain and back and forth through both hemispheres, connecting reciprocally with neurons in the thalamus (sensory relay station) and in the cerebral cortex. These neurons are focusing attention, receiving sensory news and assessing it, repressing the irrelevant, reactivating long-term memory circuits, and, by comparing the new and the known, registering a felt sense of “satisfaction” or “truth,” which is brought home by a surge of the reward system (mainly dopamine).

Crick and Koch propose, rather, that the part of our gray matter necessary for consciousness is the claustrum, a structure flat as a sheet located deep in the brain on both sides. Looked at face-on, it is shaped a bit like the United States. This claustrum maintains busy connections to most other parts of the brain (necessary for any conductor role). It also has a type of neuron internal to itself, able to rise up with others of its kind and fire synchronously. This may be the claustrum’s way of creating coherence out of the informational cacophony passing through. For consciousness feels coherent. Never mind that your brain at this moment is processing a zillion different data bits.

Gerald Edelman’s (global) theory of consciousness sees it resulting from neuronal activity all over the brain. Edelman (along with Changeux and others) applies the theory of evolution to populations of neurons. Beginning early in an individual’s development, neurons firing and connecting with other neurons form shifting populations as they interact with input from the environment. The brain’s reward system mediates which populations survive as the fittest. Edelman’s theory speaks to the fact that no two brains are exactly alike; even identical twins do not have identical brains.

How, in Edelman’s scheme, does consciousness achieve its coherence? By the recirculation of parallel signals. If you are a neuron, you receive a signal, say from a light wave, then relay it to the next neuron via an electrical pulse. Imagine a Fourth of July fireworks, a starburst in the night sky. Different groups of neurons register the light, the shape, the boom. After receiving their respective signals, populations of neurons pass them back and forth to other populations of neurons. What emerges is one glorious starburst.

I myself do not have a theory of consciousness. Still, I am a conscious (occasionally) being. My sense of myself, my sense of an “I,” has some sort of neuronal correlate. I am conscious (aware) of the fact that I am teaching a writing seminar (observed object with neuronal correlate) on the literary form known as the abecedarium (observed object with neuronal correlate). I am conscious (aware) that I will be submitting my own abecedarium—this one—to the brainy writers in the class. Because I can imagine the future, because I can plan ahead (thanks in part to my frontal lobes), I feel apprehensive. How crazy! To imagine I could comprehend the Homo sapiens brain, the most complex object in the known universe, within the 26 compartments of an abecedarium.

I will try. I will color the cones and rods and convoluted lobes printed in black outline in my anatomy coloring book. I will teach my neurons to know themselves. As I write this, I picture our class seated around our big table. I can picture the face of each writer at the table. To each face I can attach a name. This is proof that, as of today, I have dodged dementia.

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