ron in a small piece of brain tissue was stained in this way, the result
would be a glob of dark-colored mess, so densely packed with silver
chromate that it would be useless to look at in hopes of seeing indi-
vidual cells. But the most amazing thing about the Golgi stain is that
it is woefully inefficient, only about 1 percent of neurons are stained!
These 1 percent are stained really well, and the remaining 99 percent
aren’t stained at all. Neuroscientists have been using Golgi’s staining
method for more than a century, and yet it is still not known why only
some neurons are stained. They appear to be a kind of random subset
of the neurons present. Perhaps it has something to do with being
recently active, or inactive, or something else about the recent state of
the cell’s physiology. Such little mysteries are sweet!
And so, by the beginning of the twentieth century, here was the broad
scenario: brains and nervous systems were understood as highly so-
phisticated networks for connecting sensory information with move-
ment, having evolved in the animal kingdom to facilitate survival
while moving around in complex and challenging environments.
Signaling in the nervous system was electrical in nature—meaning
that it involved the movement of charged particles. These charged
particles were likely to be atomic in nature. The brain was appreciated
as being somehow central to the functioning of the mind—mental ex-
perience and consciousness. Developments in the sciences of physics
and chemistry made it increasingly attractive to try to understand the
phenomena of life at as microscopic a level as possible—that of cells
and molecules. There were many mysteries, many questions—but the
future of the life sciences looked bright.
Nerve currents sparkle.
A trillion nodes resonate.