The Root of Thought (3 page)

Of course, these ideas were placed at the end of a paper in 1894 on the introduction of local anesthesia, Schleich’s main contribution to medicine. In the same year of Schleich’s publication, Sigmund Exner (1846–1926) published a neuron-only view of cell communication in the brain.

Three years earlier, Wilhelm Gottfried von Waldeyer (1836–1921) coined the term neurone to describe specific cells with long processes. Looking at these cells, Exner was the first to specifically claim how they were the most important cells for information storage in the brain. With crude drawings of grids and a pared down view of the seat of intelligence, Exner elucidated the method of neuron transmission. Cajal took the theory as his own, and then expounded and improved upon it. Each cell was separate and not connected as Golgi thought.

Schleich’s idea of glial signaling was lost in the shadows of the luminous idolatry of Exner and Cajal. The importance of the neuron was given the term the Neuron Doctrine. And like any doctrine, it was built on faith.

The priests of the Neuron Doctrine set about trying to reconcile how they could account for this abundant glial cell without knocking the neuron off its pedestal. Carl Weigert (1845-1904) proposed a popular theory based on Virchow’s original idea in 1858 that glia were simply structural elements or glue. Now that it was known that the long, sinewy tendrils extending from the brain into the spinal cord and out to the muscle were the processes of neurons, could it be that glial cells were just structural elements that filled space unoccupied by neurons—the neural putty everyone originally thought it was? Cajal wasn’t sold. But then his brother Pedro adopted the idea and put forth that glia were simply insulators that prevented the undesirable spread of neuronal impulses. Cajal agreed and glia were pushed to the back burner. This idea is still taught today.

Maybe as a cruel joke, the Nobel Prize committee decided to give Golgi and Cajal the Nobel Prize in Medicine jointly in 1906. It was time for a showdown. Golgi was allowed to talk the day before Cajal, because without the Golgi stain, Cajal’s research would not exist. The speeches were tense, with Golgi titling his talk, “The Neuron Doctrine: Theory and Facts.” After introducing the theory, he went on to say, “While I admire the brilliancy of the (neuron) doctrine, which is a worthy product of the high intellect of my illustrious Spanish colleague, I cannot agree with him on some points of an anatomical nature, which are, for the theory, of fundamental importance…” Golgi firmly believed in a nervous organ working as a reticulum, with cells physically connected and comprised of glia as a neuronal booster through its access to the blood stream.

Knowing Golgi had for some time gone out of favor among scientists and knowing Golgi was now an Italian senator and less inclined to keep up with modern science, Cajal simply stuck to his guns in his speech the next day. Cajal defended his theory by citing Waldeyer, Exner, Deiters, and Kolliker, staying above Golgi’s potshots and stating the facts as he saw them. Neurons were all separate cells and not physically connected. He didn’t mention glia. Later, he wrote he was furious at Golgi for his “display of pride and self-worship.” He said Golgi’s ego was “hermetically sealed… and impermeable to the incessant changes taking place in the intellectual environment.”

Although Golgi also believed in a secondary importance for glia, he perceived a more active role than Cajal. But after the dust settled, neurons had won and glia were forever obscured to oblivion, the byproduct of the brain child of Santiago Ramón y Cajal’s brother Pedro. This was not the equivalent of Billy Carter being asked by Jimmy what he thought of the Iran hostage situation. Pedro was a satisfactory scientist in his own right, but it was still strange for Cajal to toss aside a cell he had helped illuminate through his meticulous studies. Not to mention the most abundant cells in the brain. The Neuron Doctrine fit together nicely, the way he liked it, and the neuron was contrary to Golgi, which was also the way Cajal liked it.

The modern study of neuroscience was born, and Santiago Ramón y Cajal became the father of the field. Cajal made sure to let everyone know what was right and what was wrong. And Golgi’s skewering by Cajal at the Nobel Prize ceremony did not encourage detractors. Glia went unstudied for six decades.

Azmitia, E.C., J. Defelipe, E.G. Jones, P. Rakic, and C.E. Ribak.
Progress in Brain Research: Changing Views of Cajal’s Neuron
. Elsevier, New York: Elsevier Science, 2002.

Clarke, E. and L.S. Jacyna.
Nineteenth-Century Origins of Neuroscientific Concepts
. Los Angeles, CA: University of California Press, 1987.

De Vellis, J.
Neuroglia in the Aging Brain
. Totowa, NJ: Humana Press, 2002.

Finger, S.
Origins of Neuroscience: A History of Explorations into Brain Function
. New York: Oxford University Press, 1994.

Kettenmann, H. and B.R. Ransom.
Neuroglia
, Second Edition. New York: Oxford University Press, 2005.

Ramón y Cajal, S.
The Neuron and the Glial Cell
. Springfield, IL: Charles C. Thomas Publisher Ltd., 1984.

Shepherd, G.M.
Foundations of the Neuron Doctrine
. New York: Oxford University Press, 1991.

Verkhratsky, A. and A. Butt.
Glial Neurobiology
. Chichester, West Sussex: John Wiley & Sons Ltd., 2007.

Romans in ancient times were probably wise to avoid the doctor if they had a headache. If you traveled through time to ancient Rome, and the trip gave you a headache, you might want to just grin and bear it. If you went to the doctor, he would go to his saltwater tank and delicately scoop up an electric fish (not with his hands) and touch your forehead with it, shocking the headache out of you. Although not entirely understood, the human species has known about the existence of electricity since the first evolved human saw a lightning storm. Smashing some rocks together produced sparks, and after metallurgy, so did the metallic crashing of swords. Of course, electric rays and fish were pondered as far back as the ancient Greeks. Why Romans thought applying the shock of a fish to the head would cure a headache instead of exacerbate it is beyond the scope of this book.

When glia were discovered after the advent of cellular stains, and immediately discounted, it was the direct result of the characterization of electricity in the eighteenth and nineteenth centuries. Ramón y Cajal’s Neuron Doctrine and acceptance of Pedro’s glial theory that followed were based on the view of the supreme importance of electrical signaling in neurons. It is now known that all cells have an electrical potential and gradient.

In the eighteenth century, electricity was the rage in science. It was the equivalent of quantum physics today. Everyone in the scientific field had a theory or insight into the origins of electricity and the applications of it. It was a mysterious phenomenon that could be the wrath of God, the golden tendrils of angel’s tears, or the teetering spark of universal destruction. Now we believe electricity is essentially a normal byproduct of living in an atomic world, and harnessing it might have been the most important advance in human history.

In the biological field, the first experiments attempted to describe how physical beings are able to conduct electricity were on electric eels and electric rays. The anatomy of the electric ray was described by John Hunter (1728–1793) in 1773, around the same time that scientist John Walsh (1726–1795) described the electrical properties of the torpedo fish, or ray.

Walsh equated the electrical activity of the fish to the Leyden jar, a device used to condense electrical potential. Developed by Pieter Van Musschenbroek (1692–1761) in the late 1740s and named after the Dutch city where he created it, the Leyden jar used wires to conduct frictional electricity into a flask of fluid. The fluid would build up electrical potential and a shock could be administered through a wire coming out of the jar. Walsh believed the fish was able to take outside electrical fluid and concentrate it within its body and shock other fish for it to devour. Hunter thought the fish was able to “will” the electrical power.

Knowing the Leyden jar could shock a person, scientists naturally took the idea to cadavers. There’s nothing like shocking a dead guy on a sunny Saturday afternoon. Using the Leyden jar, scientists noticed muscular contractions in the cadavers. The convulsions of the dead when shocked electrically led to many speculations of the nature of electrical conductance in man. But knowing our bodies contain fluid, the idea needed to be investigated more thoroughly because our bodies might act like the fluid at the bottom of the Leyden jar, passively conducting it through rigid muscles.

The Leyden jar was used for entertainment as well. In the court of Louis XIV in Versailles, 180 French soldiers were lined up holding hands with metallic disks in the palms. When a soldier on the end touched the Leyden jar output, it was conducted through the entire train of people to the other end. One poor soul was shocked by touching the last man with his bare hand. This was replicated by 700 monks at a Parisian abbey to demonstrate the power of conductance through our bodies.

However, inherent electricity in a life form was still reserved as an aberration of the electric fish. People weren’t going around shocking each other like Emperor Palpatine in
Star Wars
. But a cat’s hair standing on end in the presence of a hand or a finger shock caused thoughts of the possibility. Mostly, evidence pointed to the fact that we are wet bodies unable to summon electricity, only to passively conduct it through our presence.

Much of the excitement over electrical phenomena resulted from the research of Benjamin Franklin (1706–1790) in 1751. His portly, rotund physique and stately demeanor, with glasses on the end of his nose, affecting a glance at you, deterred his gaze at important work. Yet, behind those wizened eyes, Franklin could express love and castigation paradoxically at the same time. In a quick glance from him was the ultimate human representation of provocative thought. He’s an odd person to contemplate when you lay down a hundred dollar bill on a blackjack table. Without electricity, there would likely be no United States because lightning gave Franklin the credibility to be a voice for a revolution.

Franklin demonstrated the equal and opposing electrical action and coined the terms “positive” and “negative” electricity. The inside of the Leyden jar was positive and the outside was negative to Franklin. Franklin wouldn’t have any trouble “jumping” his car. He used his ideas to develop a metal plate to conduct electricity. The plate became known as the Franklin square.

After Franklin’s work, and the convulsions of dead bodies when electrically stimulated, scientists had the necessary tools to research electricity as the nature of animal movement. Electricity seemed to be a candidate that could finally explain and justify Galen’s humors (the yellow bile) and Descartes’ spirits. Even Newton had a similar idea. He claimed the ether in our nerves pervades every aspect of life and that humans can control it in our nervous fibers. Electricity fit the bill for the Newtonian vision as well.

By 1780, Franklin’s theories and descriptions of the Leyden jar were generally accepted and widely read throughout Europe. Like Thomas Edison in the late nineteenth century, Luigi Galvani (1737–1798) took Franklin’s knowledge and revolutionized the meaning of electricity. Galvani, a reclusive scientist working at the University of Pavia, the same university where Golgi would discover his stain 100 years later, applied Franklin’s theories to dissected frogs to see if animals have an intrinsic electricity, and more specifically, if this intrinsic electricity could be the conductor that causes physical action.

Galvani dissected the frog’s spinal cord, leaving the legs and leg muscles intact. His drawings of the experiments look like the legs were torn off Kermit the Frog’s body by a maniacal mass murdering puppeteer (see
Figure 3.1
). Legend has it that he prepared the frog legs for his sick wife’s dinner and got the idea while abstractedly bending them up and down. Hopefully, she got something else to eat that night.

FIGURE 3.1 Doc Galvani’s fried frog legs

Jan Swammerdam (1637-1680), a Dutch biologist with an awesome name, was the first to dissect the frog muscle and nerve. Galvani was the first to shock them. Using the Leyden jar or the Franklin square (Galvani called it the magic square), a current was conducted through the tinfoil-wrapped spinal cord with the legs contracted. Galvani also hooked the legs to a wire on an iron rail in his garden in order to observe atmospheric electrical influences on the legs. However, bored with waiting because storms in Italy didn’t arrive on command, he began to introduce different metals to the lightning rod and observed leg contractions. He realized that an inherent potential existed in the animal based on these experiments.

A curious development began as an offshoot of Galvani’s theories. Controlling physicist Alessandro Volta (1745–1827) didn’t believe Galvani understood all the current research in electricity over the 40 years since Franklin published his original work. An original Galvani supporter, Volta now believed that the reason for leg contractions was similar to the reasons that electric shock was produced in bodies when presented with an electric current, and this might not be due to inherent animal electricity at all. He thought the two opposing metals created the
current, and the body simply acted as a fluid through which it was conducted, as previously explained by the convulsions of a cadaver and the French Legion with the Leyden jar.