Page 88 - Darwin's Dilemma: The Soul

Darwin’s Dilemma: The Soul

letter is a symbolic description of your bedroom.

What is meant by a symbolic description in the brain? Not squig-
gles of ink, of course, but the language of nerve impulses. The hu-
man brain contains multiple areas for processing images, each of
which is composed of an intricate network of neurons that is spe-
cialized for extracting certain types of information from the image.
Any object evokes a pattern of activity—unique for each object—
among a subset of these areas. For example, when you look at a pen-
cil, a book or a face, a different pattern of nerve activity is elicited in
each case, “informing” higher brain centers about what you are look-
ing at. The patterns of activity symbolize or represent visual objects
in much the same way that the squiggles of ink on the paper sym-
bolize or represent your bedroom. As scientists trying to understand
visual processes, our goal is to decipher the code used by the brain
to create these symbolic descriptions, much as a cryptographer tries
to crack an alien script. 51
But the mere existence of this map does not explain seeing, for as I
noted earlier, there is no little man inside watching what is displayed
on the primary visual cortex. 52
Richard L. Gregory offers this description:

It is important to avoid the temptation of thinking that eyes produce
Axon

When we look at a book, a pencil or a hu-
man being, a different nervous activity
goes into operation for each object per-
ceived. The higher brain centers are in- Synaptic ending
formed about what we are looking at.
However, the countless chemical process-
es involved here are not by themselves
sufficient to account for sight, because
there is no little person observing the im-
ages in the brain. It is the human soul
that observes the external world and
draws significance from it.

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