Is the human brain, with all its problem-solving prowess and creative ability, powerful enough to understand itself? Nothing in the known universe (with the exception of the universe itself) is more complex; the brain contains about 100 billion nerve cells, or neurons, each of which can communicate with thousands of other brain cells.
From This Story
Because we primates are primarily visual creatures, perhaps the best way for us to make sense of the brain is to see it clearly. That has been the goal for 125 years, since the Spanish scientist Santiago Ramón y Cajal began using a stain that marked individual neurons. He peered through a microscope at the stained cells and the branchlike projections with which they connected to other neurons. “Here everything was simple, clear and unconfused,” he wrote of his observations, the beginning of modern neuroscience.
Scientists have since devised methods for determining the specific tasks in which different brain regions specialize—for example, some neurons, devoted to processing sight, detect only horizontal lines, while others sense danger or produce speech. Researchers have created maps delineating how brain regions not adjacent to one another are connected by long tracts of cellular projections called axons. The newest microscope techniques reveal neurons changing shape in response to experience—potentially recording a memory. The ability to see the brain in a fresh light has given rise to a wealth of insights in the past few decades.
Now scientists’ forays into this universe are being put to a different use—as art objects. Carl Schoonover, a neuroscientist in training at Columbia University, has collected intriguing images of the brain for a new book, Portraits of the Mind (Abrams). “They are real data, not artists’ renditions,” he says. “This is what neuroscientists are looking at in their microscopes, MRI machines or electrophysiology systems. Neuroscience exists because of these techniques.”
By borrowing a gene from fluorescent jellyfish and inserting it into the DNA of worms or mice in the lab, scientists have made neurons glow. Cajal’s staining technique worked only on post-mortem tissue, and it marked neurons randomly, but the new dyes have enabled scientists to “study neurons in living animals and tissues,” Joshua Sanes of Harvard University notes in an essay in the book.
One of the newest methods relies on a gene that makes algae sensitive to light. Shining a light on neurons containing the gene can change their behavior. “The advances allow us to manipulate the activities of individual cells and cell types using beams of light,” writes Terrence Sejnowski of the Salk Institute for Biological Studies.
The brain remains mysterious, but the patterns in these images—rich whorls of neural connections, unexpected symmetries and layers of structure—encourage scientists to believe they will yet decipher it. For his part, Schoonover hopes to “make readers think it’s worth trying to figure out what the images are and why they are so beautiful.”
Laura Helmuth is a senior editor for Smithsonian.
Photographs are from Portrait of the Mind: Visualizing the Brain from Antiquity to the 21st Century by Carl Schoonover, published by Abrams.