HOW THE BRAIN MAKES POTENTIAL 171
A QUICK RECAP AND WHAT THE BRAIN
MIGHT BE FORChapter 4 spelled out just what a real- world environment means. Th e
upshot was that complex organisms evolved in highly changeable worlds,
but ones full of spatiotemporal patterns. Th e patterns contain information
deeper than simple associations and are assimilated, even in molecular
networks, as statistical (relational) par ameters. Th ese are a kind of knowl-
edge and help predict the consequences of responses. So responses can be
optimized even in novel situations.
Th is is the intelligence of the cell. Such information cannot be found
in genes per se, laid down by the experiences of past generations. It has to
be abstracted de novo from con temporary experience.
Chapter 5 showed how the intelligence of the cell has been extended
in development and physiology in multicellular organisms. Th ese func-
tions evolved to provide increased adaptability in even more changeable
environments. A major feature, even at those levels, is the presence of
compensatory (alternative) pathways to form, function, and their develop-
ment. With so many idiosyncratic expressions, it is impossible (as well as
pointless) to arrange individual diff erences along a single functional axis
valid for all circumstances. For the vast majority of cells and organisms,
their functions are good enough for the challenges faced.
Th is chapter extends that theme. I show how the evolution of ner vous
systems and brains was the continuation of a trend in the evolution of in-
telligent systems. Th is implies that the essential currency of the brain, and
the cause of its development and its variation, is also the statistical struc-
ture of the environment. But now that structure is on a stupendous scale.
Instead of broadcast hormones, or local cell junctions, communication
in the brain is through electrochemical signals channeled down long
fi bers (axons) culminating at specialized connections (synapses) on shorter
fi bers (dendrites) of receiving cells. A neuron can form synapses on poten-
tially hundreds or thousands of other cells. At each of them, it sends and
releases a neurotransmitter to activate receptors on the synapses.
Not only is this fast and to the point, but synapses are also specialized
for integrating the statistical (structural) information from large numbers
of other neurons. Th ey can modify connectivity in the pro cess, enhancing
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