Consciousness
Forget about the mind as a computer. It's more like a high-speed
version of "survival of the fittest," where individual thoughts compete
for cerebral dominance, says a University of Washington
neurobiologist.
Scientists have long known that colors, memories, and other mental
info is coded within patterns of tiny electrical impulses fired by groups
of nerve cells. William Calvin, Ph.D., suspected these firing patterns
were self-perpetuating--that is, they could somehow clone
themselves.
He also suspected that these cloned patterns then competed with
other patterns for mental "territory." The winners, Calvin theorized,
went into mass production, amplifying the original firing pattern--and
its coded information--into what we call conscious thought.
But how did these forms reproduce? And what Darwinian force
selected the winners?
Other research provided some clues. In certain neuron clusters the
axons, or long arms of nerve cells, showed uniform length. This meant the
firing pattern in one nerve cell could easily "fit" an adjacent cell. In
fact, Calvin says, one cell's pattern can begin resonating spontaneously
within a neighboring cell through a process called "entrainment." In
short order, a single firing pattern can strike up an entire duster of
nerve cells.
Calvin says such clusters, roughly hexagonal in shape and a half
millimeter across, form the basic unit of consciousness. Each contains a
parcel of coded information. Each works to recruit neighboring hexagons
through entrainment. If successful, each hexagon multiplies into a vast
mosaic through the cortex, and the larger the mosaic, the "louder" its
firing pattern. Our internal " narrator," Calvin speculates, may simply
be a string of the most dominant firing patterns.
Now comes the Darwinian part. Hexagons aren't permanent. Electric
waves of neural inhibition periodically flash through the cortex, erasing
hexagons.
Yet once a hexagon has been imprinted by a firing pattern, Calvin
posits, it will fat pattern.
Even if erased, the hexagon will respond most readily to future
stimuli in the same pattern--whether the stimulus comes from an adjacent
hexagon, via entrainment, or from another brain region, via axons. In
short, the more often a firing pattern is produced--e.g., the more often
the visual cortex codes and stores "apple"--the more likely that pattern
will achieve dominance and become conscious thought. just as with a
species, Calvin says, "the more a hexagon reproduces, the greater the
chance that it will be produced."
Competition between hexagons maybe how we compare different ideas
or objects, with the winning hexagon forming the basis of our
conclusions. And when hexagons compete, they try recruiting, or
entraining, each other. The struggle produces hybrid hexagons with hybrid
firing patterns--thus, hybrid thoughts. That, Calvin theorizes, may
explain how we "create novel thoughts, recognize novel or ambiguous
patterns, and filter out the nonsense."
PHOTO: THE KEY TO CONSCIOUSNESS: HEXAGON-SHAPED CELL CLUSTERS.
(SPL/PHOTO RESEARCHERS, INC.)
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imprinting,
inhibition,
mass production,
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tiny electrical impulses,
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