Decades before these technologies existed, a man hunched over a microscope in Spain at the turn of the 20th century was making prescient hypotheses about how the brain works. At the time, William James was still developing psychology as a science and Sir Charles Scott Sherrington was defining our integrated nervous system.
Meet Santiago Ramón y Cajal, an artist, photographer, doctor, bodybuilder, scientist, chess player and publisher. He was also the father of modern neuroscience.
“He’s one of these guys who was really every bit as influential as Pasteur and Darwin in the 19th century,” said Larry Swanson, a neurobiologist at the University of Southern California who contributed a biographical section to the new book “The Beautiful Brain: The Drawings of Santiago Ramón y Cajal.” “He’s harder to explain to the general public, which is probably why he’s not as famous.”
Ramón y Cajal started out with an interest in the visual arts and photography — he even invented a method for making color photos. But his father pushed him into medical school. Without his artistic background, his work might not have had as much impact, Dr. Swanson said.
“It’s fairly rare for a scientist to be a really good artist at the same time, and to illustrate all of their own work, brilliantly,” Dr. Swanson said. “There seems to be a real resurgence of interest between the interaction between science and art, and I think Cajal will be an icon in that field.”
The images in “The Beautiful Brain” illustrate what Ramón y Cajal helped discover about the brain and the nervous system, and why his research had such an effect on the field of neuroscience.
Ramón y Cajal wanted to know something no one really understood: How did a neural impulse travel through the brain? But he had to lean on his own observations and reasoning to answer this question.
Ramón y Cajal’s life changed in Madrid in 1887, when another Spanish scientist showed him the Golgi stain, a chemical reaction that colored random brain cells. This method, developed by the Italian scientist Camillo Golgi, made it possible to see the details of a whole neuron without the interference of its neighbors. Ramón y Cajal refined the Golgi stain, and with the details gleaned from even crisper images, revolutionized neuroscience.
In 1906 he and Golgi shared a Nobel Prize. And in the time in between, he wrote his neuron doctrine — the theory that neurons were individual brain cells, leading to his realization of how individual brain cells send and receive information, which became the basis of modern neuroscience.
Ramón y Cajal’s theory described how information flowed through the brain. Neurons were individual units that talked to one another directionally, sending information from long appendages called axons to branchlike dendrites, over the gaps between them.
He couldn’t see these gaps in his microscope, but he called them synapses, and said that if we think, learn and form memories in the brain then that itty-bitty space was most likely the location where we do it. This challenged the belief at the time that information diffused in all directions over a meshwork of neurons.
The theory’s acceptance was made possible by Ramón y Cajal’s refinement of the Golgi stain and his persistence in sharing his ideas with others. In 1889, Ramón y Cajal took his slides to a scientific meeting in Germany. “He sets up a microscope and slide, and pulls over the big scientists of the day, and said, ‘Look here, look what I can see,’” said Janet Dubinsky, a neuroscientist at the University of Minnesota. “‘Now do you believe that what I’m saying about neurons being individual cells is true?’”
A few of his drawings had features that resembled the work of other artists. In some, Vincent van Gogh appeared influential. In this drawing of the glial cells in the cerebral cortex of a man who suffered from paralysis, the three nuclei (or nucleoli) in the upper left corner resemble Edvard Munch’s “The Scream.”
In addition to showing how information flowed through the brain, Ramón y Cajal showed how it moved through the whole body, allowing humans to do things like vomit and cough. When we vomit, a signal is sent from the irritated stomach to the vagus nerve in the brain and then to the spinal cord, which excites neurons that make us contract our stomach and heave. Similarly, a tickle in the back of your throat can make you cough: The larynx sends a signal to the vagus nerve, then the brainstem and the spinal cord, where neurons signal the muscles in our chest and abdomen to contract. Ahem.
This image is a reconstruction of a dendrite (red) and its axons (multicolored) in the outer part of a mouse’s brain. The dendrite has little knobby spines that stick out and receive chemical messages passed from another neuron’s axon across the synapse, or gap between them, via the tiny white sacs called vesicles. Today we know that synapses are plastic, meaning they can get stronger or weaker with use or neglect. This enables us to think and learn.
This is what Ramón y Cajal described in his neuron doctrine.
“People regularly begin seminars with pictures of the drawings that Cajal made because what they’ve added fits right in with where Cajal thought it should be,” Dr. Dubinsky said. “What he did is still relevant today.”
Article lead images: Illustrations by Santiago Ramón y Cajal, the Spanish neuroscientist, from the book “The Beautiful Brain.” From left: A diagram suggesting how the eyes might transmit a unified picture of the world to the brain; a purkinje neuron from the human cerebellum; and a diagram showing the flow of information through the hippocampus in the brain.