86
The Body Electric
idea that external current could replenish the vital force of exhausted
nerves became the rationale for a whole century of electrotherapy.
Modern studies of nerves and current began in 1902, when French
researcher Stephane Leduc reported putting animals to sleep by passing
fairly strong alternating currents through their heads. He even knocked
himself unconscious several times by this method. (Talk about dedica-
tion to science!) Several others took up this lead in the 1930s and devel-
oped the techniques of electroshock and electronarcosis. The therapeutic
value of using large currents to produce convulsions has been questioned
more and more, until now it's mostly used to quiet unmanageable psy-
chotics and political nonconformists. Electronarcosis—induction of sleep
by passing small currents across the head from temple to temple—is
widely used by legitimate therapists in France and the Soviet Union.
Russian doctors claim their elektroson technique, which uses electrodes on
the eyelids and behind the ears to deliver weak direct currents pulsing at
calmative brain-wave frequencies, can impart the benefits of a full
night's sleep in two or three hours. There's still much dispute about how
both techniques work, but from the outset there was no denying that
the currents had a profound effect on the nervous system.
In the second and third decades of this century there was a flurry of
interest in galvanotaxis, the idea that direct currents guided the growth
of cells, especially neurons. In 1920, S. Ingvar found that the fibers
growing out of nerve cell bodies would align themselves with a nearby
flow of current and that the fibers growing toward the negative electrode
were different from those growing toward the positive one. Paul Weiss
soon "explained" this heretical observation as an artifact caused by
stretching of the cell culture substrate due to contact with the elec-
trodes. Even after Marsh and Beams proved Weiss wrong in 1946, it
took many more years for the scientific community to accept the fact
that neuron fibers do orient themselves along a current flow. Today the
possible use of electricity to guide nerve growth is one of the most excit-
ing prospects in regeneration research (see Chapter 11).
The Bernstein hypothesis, unable
to account for these facts, has
turned out to be deficient in several other respects. To begin with, ac-
cording to the theory, an impulse should travel with equal ease in either
direction along the nerve fiber. If the nerve is stimulated in the middle,
an impulse should travel in both directions to opposite ends. Instead,
impulses travel only in one direction; in experiments they can be made
to travel "upstream," but only with great difficulty. This may not seem
like such a big deal, but it is very significant. Something seems to polar-
ize the nerve.