238
The Body Electric
Unifying Pathways
The experiments I'd done with psychiatrist Howard Friedman in the
early 1960s, mentioned in Chapter 5, were the first to provide strong
support for an analog theory of pain. In all animals, including humans,
the normal negative potentials at the extremities weakened or vanished
as an anesthetic took effect. Under deep total anesthesia, the potentials
often reversed entirely, the extremities becoming positive and the brain
and spine negative. At that time we didn't yet know about the two-way
system, inward along sensory nerves and outward along motor nerves,
but it was obvious that a current flow was being reversed by the pain-
preventing drugs. In lab animals and humans under local anesthetic,
such as a shot of procaine in one arm, the negative potential was abol-
ished only for that arm. The DC potentials over the head were un-
affected—except for a little blip in the recording that registered the
prick of the needle!
In addition, the DC potentials react slowly enough to account for
pain. A wound usually doesn't start to hurt in earnest until minutes, or
even hours, after the injury. This delay has been especially hard to ex-
plain in terms of nerve impulses, which travel at 30 feet per second.
However, when Friedman and I injured the limbs of salamanders while
monitoring the potentials on their limbs and heads, we found that the
change in the limb reading showed up in the head after a time approx-
imating that of delayed pain. Acupuncture likewise involves a delay,
usually twenty minutes or more, before its effects are felt.
We also found we could work backward, using the currents to pro-
duce anesthesia. A strong enough magnetic field oriented at right angles
to a current magnetically "clamped" it, stopping the flow. By placing
frogs and salamanders between the poles of an electromagnet so that the
back-to-front current in their heads was perpendicular to the magnetic
lines of force, we could anesthetize the animals just as well as we could
with chemicals, and EEG recordings of magnetic and chemical anesthe-
sia were identical. We got the same effect by passing a current through
the brain from front to back, canceling out the normal current of waking
consciousness, as in electrosleep.
One of the most exciting results of my collaboration with Dr. Fried-
man was proof that one's state of waking consciousness could change the
perception of pain.
Friedman,
who already used hypnosis to control
chronic
pain in his patients, gave several of his best subjects hypnotic
suggestions of arm numbness deep enough that they couldn't feel the