The Root of Thought (4 page)

To demonstrate his ideas, he stacked two opposing metals and created an electric potential. He showed that brass and iron can create an electrical potential like the Leyden jar. There is an electrical gradient between the metals that generates energy. And by applying this to an animal, convulsions would be expected. The stacked metal became known as the voltaic pile, the precursor to the modern battery. In his rash fervor to discount the quiet reclusive Galvani’s theories, Volta inadvertently invented the battery. Sadly, it is true, sometimes invention and creativity is the result of someone trying to tear down their fellow man. This discovery resulted in his name being forever associated with electrical potential.

In his experiments, Volta began introducing an electrical current to his own body by his tongue. He produced sensations of taste. By covering his eye in tinfoil and introducing a current, he produced the sensation of seeing flashes of light. Volta interpreted this to mean that his body was simply a fluid that conducted current and it did not have an intrinsic charged fluid. He told anyone who would listen to him. It’s wise to listen to a guy who’ll go so far as to cover his own eyes with tinfoil.

Galvani remained publicly quiet throughout Volta’s challenges during the seven years before he died after his original publication in 1791. The first shot across Volta’s bow was published anonymously in 1794. The nerve of a frog was cut and then applied to the nerve of an intact frog. The releasing electrical current caused the intact frog’s legs to contract vigorously. The experiment definitively proved Galvani correct. Most researchers didn’t notice the article because of the anonymity attached to its publication, and people were too busy paying attention to Volta’s rants and raves. It is now known that Galvani published the anonymous report.

The controversial theory raged for a few decades. Although Galvani eschewed the fight, Giovanni Aldini (1762–1834), Galvani’s nephew, took up the cause.

Aldini was an ardent supporter of his uncle and believed Volta conclusively wrong. In fact, Aldini went so far as to conduct experiments on newly acquired heads off the guillotine during the Napoleonic Wars. As soon as the head was chopped off, Aldini would take it to make sure it was fresh and apply currents through the ears and mouth. The decapitated
heads contracted into different facial expressions: smiling, grimacing, and coy expressions.

Aldini also presaged electroshock therapy by applying the Voltaic pile to his head and shocking himself at arbitrary strengths. He reported it as unpleasant and causing insomnia for a week. It’s probably better to stick to electric fish to the head. The contractions were of interest for those treating the mentally insane because of evidence that camphor-induced seizures were therapeutic for the clinically depressed. Shocking the hell out of you will surely get you out of a funk.

Scientists weren’t the only ones interested in animal electricity. The public and governments of researchers ardently consumed any new experiment. The public’s fascination with the subject peaked in the early nineteenth century with the publication of
Frankenstein
. Taking the frightening and grotesque scientific literature produced by Volta and Aldini, which induced hysteria similar to cloning and stem cells today, Mary Shelley, in Switzerland with her husband and poet Percy Bysshe Shelley and friend, poet George Gordon, Lord Byron, brought back the dead while telling ghost stories late at night.

With Volta still on his soapbox denouncing Galvani’s work, after
Frankenstein
, people were relieved that animal electricity might not be true. However, in Italy, Galvani’s homeland, animal electricity was still avidly pursued, with the next notable discoveries by the physicist Leopold Nobili (1784–1835) and his student Carlo Matteucci (1811–1868) in the 1830s. Using only saline after decapitating a frog, they placed the trunk in one jar and the legs in another and connected them with a cotton thread soaked in salt solution. Contractions occurred without Volta’s iron and brass metallic arc.

Many of the cellular ideas of the brain at the time were solidified in the same lab by students who all graduated around the same time from the University of Berlin. These students included German scientist Johannes Müller (1801-1858), who advised several prominent experimenters; Robert Remack (1815-1865), who determined the nerve fiber hooked up with the cell body; Hermann von Helmholtz (1821-1894), who developed the theory for the conservation of energy; Rudolph Virchow (1821-1902), who was one of the first to discover the glial cell; and finally, the one with the most forceful personality, Emile du Bois-Reymond (1818–1896), who was the father of the action potential.

Emile du Bois-Reymond came to Müller excitedly with a copy of Matteucci’s work and proclaimed his interest in pursuing animal electricity. Müller knew Matteucci had recently become frustrated with his experiments and completely denounced animal electricity—going so far as to claim that he shared Volta’s view that the nerves were filled with a non electric fluid or Newton’s ether, a belief also shared by Müller. But he decided to give his student the project to further study the earlier phenomena Nobili’s lab discovered. Du Bois-Reymond ran with the work and first developed more sensitive galvanometers to understand whether electrical potential existed.

If Volta was persuasive in his condemnation of Galvani, du Bois-Reymond was just as influential in his trumpeting of Galvani’s virtues. He replicated many of Matteucci’s experiments. But, after stimulation, he measured electrical conductance moving along the nerve to the muscle. He then was able to determine the speed of the conductance after causing contractions in the frog nerve. He determined that from stimulation to contraction, the speed was 30–40 meters per second. This is similar to what is reported today. But a problem then was that it was much slower than the electrical conduction that occurred through a wire.

Many other Descartes’ vitalists who believed that the functions of a living organism are due to the hydraulic pumping of fluids still searched for the essential element and sided with Volta claims and Matteucci’s flip-flop as evidence for electrical falsity. But du Bois-Reymond portrayed their thinking as moronic. He called vitalism pernicious and went so far as to say, “In one word, the so-called vitalism, of the type as it is currently presumed to be present in all points of the living body, is nonsense.” He had no place in his heart for detractors and mercilessly lambasted Matteucci, the man whose research got him his start, to a side note in nervous-system history.

This problem of slower electrical conduction was not resolved until chemists understood that electrolyte solutions conducted electricity at slower rates. The electrical potential in nerves is now understood to be a difference between potassium and sodium ions. Sodium ions outside the cell and potassium ions inside create an electrical potential based on ionic charge difference.

As du Bois-Reymond perpetuated the idea of electrical conductance in the fiber, Remak’s studies showed the neuron is where the fiber originates. Finally, to open the way for the electrical neuron to gain its level of
importance in the notion of our thoughts, and continuing with the belief that thoughts originate in the cerebral cortex of our brains, in 1870, the first demonstration of cortical function was achieved by Gustav Fritsch (1837–1927) and Eduard Hitzig (1838–1907). Dog cortices stimulated by electricity showed that motor control originated from the grey matter. They removed the skull and applied an electrical current through flat electrodes that would not damage the cortex. They noticed that movement occurred on the opposite side of the body from where they stimulated the cortex. They also showed that different parts of the cortex were responsible for different types of body movements. If they stimulated in one area, the dog would extend its leg; stimulation in another area resulted in the dog contracting its leg.

The backlash to their published work was immediate. Every eminent physiologist of the day called the experiments false and fabricated because they contradicted the prevailing edict that deep brain centers initiated movement. However, just as Galvani’s experiments were replicated easily by other experimenters, so were Fritsch and Hitzig’s. Cortical control of movement was soon noticed in the monkey as well.

Five years later, Richard Caton (1842–1926) came along and discovered changes in electrical activity while recording different areas of the cortex after stimulating the eyes and rotating the heads of monkeys and rabbits. Sensory nerves carried electrical impulses in the same manner as the motor nerves that cause muscular contractions.

Then Ramón y Cajal combined everyone’s work and developed his palpable Neuron Doctrine. All our experiences, imagination, creativity, and memory reside in these beautiful cells, with their dendritic trees sticking out the top like poofs of scraggly hair, their triangular-shaped cell bodies as uniform as a doll’s face, with their elegant transmitting axons each extending electrically out like the torso of a lover.

The tricky little problem was the glial cell. Cajal’s acceptance of Pedro’s theory that glia exist to buffer the electrical firing in neuronal communication came before it was understood that almost all cells have an electrical potential and gradient.

The electrical revolution ended 100 years after Galvani’s work. The foundation was set for studies on the root of thought. As Walt Whitman asked, “And if the body were not the Soul, what is the Soul?”

But Fritsch and Hitzig’s studies showed only a simple movement, and all electrical stimulation studies of neurons since have focused on reflexes
and stimulation of base desires. Ablation studies and examining the consequences of injuries allowed researchers to understand what cortical area was responsible for speech (left temporal cortex), hearing (temporal), and vision (occipital). What about the cells in the cortex—an area dominated by glia?

The assumption from electrical and cellular studies presented until the twentienth century was that the neural cell body was responsible for everything. Its axon was shown to extend from the brain to the body. And now that it was known to be electrical, all the thoughts in our brain were believed to stem from this electrical pulse in the peripheral nerves demonstrated by Galvani.

In the twentieth century, by placing neurons in a vacuum tube with sensitive electrodes with such small points they could stab into a small bundle of axons, scientists were able to accurately judge the electrical conductance in an axon. Britain’s Charles Scott Sherrington (1857–1952) developed ways to scientifically study reflexes. He coined the understanding of the synapse as the interstitial space between neurons the year Golgi and Cajal received the Nobel Prize and would win the Nobel Prize himself in 1932. The incremental notion of separate cellular structure by Sherrington and Cajal eliminated Golgi’s concept of the syncytium.

At the end of an axon, the synapse is the breach between communicating to the next neuron. The first molecule discovered to transmit across the synapse was acetylcholine at the muscles (the chemical compound that activates muscles and is a major neurotransmitter in the autonomic nervous system). Subsequently, nicotine was known to mimic acetylcholine. Scientists looking at the action of drugs discovered many of the other currently known transmitters. Cocaine led to the discovery of dopamine, morphine/heroin led to the discovery of serotonin, marijuana led to the discovery of cannabinoids, and nitrous oxide led to the discovery of nitrous oxide. These molecules are important transmitters between cells.

The eventual accurate “in-depth” reporting inside an axon was accomplished with a giant squid axon. British scientists Alan Hodgkin (1914–1998) and Andrew Huxley (1917–) and half brother of famous writer Aldous Huxley) inserted an electrode through a single axon and determined the resting potential as –60 or –70 millivolts in 1939. In 1908, Walther Nernst (1864–1941) published an equation that predicted electrical potential based on electrolyte distribution. When measuring
extracellular and intracellular space, nerves would have –85 to –90 based on the equation. This was eventually reported by Australian scientist John Eccles (1903–1997) in the 1960s. All of these men would win the Nobel Prize.

But all of this groundwork was been done in long peripheral axons extending to the body. It has been done on simplistic relexes. Not at the cellular level in the brain. The studies have revealed a lot about the neuron, but have only been able to infer how we think on a cellular level.

It is commonly believed that neurons transmit to each other constantly and that our senses solidify some connections while reducing the influence of others. They either fire or don’t. This “all-or-nothing” firing is believed by some to control thought through a binary code. This constant firing is how our thoughts happen. However, the seat of imagination and the provocateurs of neural action would be best served in a different type of cell, a cell that controls the reflexive action of axonal conductance. This cell is not firing long distance electrical sparks, but is a cell capable of activating like Golgi’s syncytium and capable of storing information through attached processes, like billions of octopi that fuse their arms to each other. It is an autonomous cell that creates, imagines, and influences the activity of its active neuronal highways.

This cell likely resides in the cortex. Although Pierre Flourens (1794–1867) and others had difficulty pinpointing areas of the cortex that corresponded to thought it was known that by removing the frontal
lobe in monkeys, they became more docile according to the work of Scottish scientist David Ferrier (1843–1924). Ferrier claimed the monkeys had no discernible post-operation deficits other than tranquility. The frontal lobotomy to treat violent patients came directly out of his descriptions of a tame monkey.