The world casts its light through the cornea and lens and onto the retina, a paper-thin mask of tissue at the back of the eye made of the same cells that make up the brain. There images are converted to electrical signals and sent to the occipital lobe, where the information is processed back into imagery.
In the blink of an eye — less! — we see.
Santiago Ramón y Cajal had a particular affection for retinal neurons. An artist before he became the father of neuroscience, Cajal peered through his microscope at neural cells. He studied and synthesized what he saw, and then he picked up a pen. “The Beautiful Brain: The Drawings of Santiago Ramón y Cajal,” at the MIT Museum through Dec. 31, attests to what a remarkable artist the scientist was.
Cajal was born in 1852, a doctor’s son in a poor town in northeastern Spain. His father discouraged his passion for drawing. He wanted the boy to be a doctor, and brought him along to anatomy classes he taught at a nearby medical school. There Cajal found a path that kept faith with his own fascinations, and satisfied his father, too. A spiritual heir to Leonardo da Vinci, he loved rendering anatomical dissections.
But Leonardo worked in a time that didn’t throw up walls between art and science. Cajal had to choose, and until now, his works have been viewed as illustrations in science books — although Surrealists such as Salvador Dali and Luis Buñuel knew his work, which after all depicted odd figures and forests within the mind.
Interested in research more than treatment, Cajal turned to histology, or cell theory, a discipline that had flowered since the introduction of powerful microscopes in the 1830s.
“I should feel myself happy in contemplating the captivating spectacle of minute life in my forgotten corner and listening, entranced, from the ocular of the microscope, to the hum of the restless beehive which we all have within us,” he wrote in his autobiography, “Recollections of My Life.”
Don’t let his lyricism fool you. The humble histologist had a flare for self-presentation, evident in his prose and in several photographic self-portraits on view. He was as skilled at photography as he was at drawing.
Cajal had reason to puff up. His thinking moved the field of neuroscience forward by leaps and bounds. He shared the 1906 Nobel Prize for Physiology or Medicine with Camillo Golgi, another neuroscientist.
Golgi was a proponent of Reticular Theory, which proposed the brain was a single contiguous network, while Cajal developed the rival Neuron Doctrine, suggesting the brain was composed of discrete cells. Two decades after he died, in 1934, Cajal was proved correct.
Think of the dry, informative diagrams in your high school biology textbook. The 80 works here are nothing like those. Cajal imbued his drawings with vigor and fancy, employing a fluid hand, attunement to composition, and a twinkle in his eye. In one image of injured neurons, the bloat of a vacuole and the dark round of the cell body look distinctly like a penguin taking a dip.
But he was only rarely cheeky. Most of his drawings hum like that restless beehive. A rendering of a sliver of a child’s cerebral cortex focuses on glial cells, which have a variety of functions other than transmitting information.
At the top of Cajal’s sheet, they drop from the surface of the brain like scraggly weeds and float about below as kinky starbursts, each labeled by a letter. Adjusting line density and the tightness of the knotty little branches, he makes each an individual. The drawing is a compelling diagram, an environment, a scene with many players.
Cajal also developed the Theory of Dynamic Polarization, which poses that information flows in one direction — into a neuron’s dendrites, through its cell body, and out its axon. He was right about this one, too, and Golgi, who imagined dendrites as tree roots, was again wrong.
Dendrites do look tree-like; they have fine hairs called dendrite spines. Cajal discovered these, too. Neuronal structures became visible through a staining process Golgi devised that enabled histologists to map cells; at first, the dendrite spines were thought to be a side effect of the stain. Cajal improved on that method and proved the spines’ existence. One wonders if Golgi admired or despised him.
“In our parks are there any trees more elegant and luxurious than the Purkinje cell from the cerebellum . . . ?” Cajal wrote of neurons named for the Czech biologist Jan Purkinje. He loved sketching Purkinje cells. In one drawing, the neuron branches like an old oak, filling the page with dendrites and dendrite spines whose paths seem at once symmetrical and meandering.
The exhibition, a traveling show organized by the University of Minnesota’s Frederick R. Weisman Art Museum, matches Cajal’s drawings with contemporary brain imaging — here, supplemented by luminous pictures straight from MIT labs, including whiz-bang interactive touchscreens that let you vault through illuminated brain matter as if you were the USS Enterprise shifting into warp drive.
A visualization by Joseph Priller of a mouse’s Purkinje cell indicates how much Cajal got right. Only the tones change: The curving trunk and dense branches are fluorescent green on red, not black ink on aging white paper.
Cajal didn’t have MRIs or touchscreens. What he had were his eye, his talent, and his passion — or perhaps it was the idiosyncratic way his brain processed what his retina caught, then passed to his hand. He saw a world in a microscope slide, and translated the life of that world onto paper.
THE BEAUTIFUL BRAIN: The Drawings of Santiago Ramón y Cajal
At MIT Museum, 265 Massachusetts Ave., Cambridge, through Dec. 31. 617-253-5927, mitmuseum.mit.edu/exhibition/beautiful-brainCate McQuaid can be reached at email@example.com. Follow her on Twitter @cmcq.