After the stroke, she could no longer paint on canvases mounted vertically, so she laid them flat, moving around them in a chair with wheels. She learned how to work with her left hand; it had less fine motor control but was more free and natural in its movements. She began to use different, less toxic types of paint, which led to new kinds of visual effects.
And she began to more deeply explore the beauty of blood vessels in the brain after seeing some of her own brain scans.
Critics called the new work intuitive and raw, more vibrant, abstract, expressive.
Photos: The artistic expressions born of brain disorders
Her attitudes too had changed: "The paint I was now using started to crack — and before the stroke, I would've been horrified," she says. "But after the stroke, I thought it looked interesting and, I believed, was part of the metaphorical language of the painting. Also, I really saw the paintings confirming my ability to live."
For Sherwood, the brain damage and resulting shift in her art led to awards, museum shows and a whole new level of critical acclaim. For scientists, experiences like hers are helping shine light on the workings of the brain.
In growing numbers, people with Alzheimer's, migraines, autism, epilepsy and more are picking up paintbrushes or putting drawing pencils to paper. Some are artists like Sherwood who continue to produce prolific portfolios after brain damage and find their work dramatically changed. Others turn to art only after a disease has set in, and they may even be inspired by it. Both groups are helping researchers unravel the complicated and intertwined ways that biology produces creativity — including the contributions of inhibition, obsession and other personality traits. "There are virtually no situations where brain damage makes things better," says Anjan Chatterjee, a neurologist at the University of Pennsylvania in Philadelphia, who is working on a book about art and the brain. But art is, he adds, one of the few complex aspects of human cognition that doesn't necessarily get worse.
"Think of a mobile where you have different weights that settle into some kind of equilibrium," he says. "If you take away certain weights, the whole system readjusts. In some instances, the art ends up being just as beautiful.
"In other cases, it's more beautiful."
Lester Potts had never picked up a paintbrush before his Alzheimer's diagnosis in 2001, at the age of 72. He had worked in a rural Alabama sawmill through the Great Depression. He served in the Korean War and grew into an even-keeled and dependable civic leader. But when his brain disorder struck, Potts lost the ability to take care of himself, and he sank into depression.
Painting with watercolors as part of a therapy program buoyed him, says his son, Daniel C. Potts. Even more surprising, his father had talent. When Lester brought home his first creation — a bright purple and yellow hummingbird with green wings and a red head — his wife asked him who gave him such a beautiful painting.
As Lester's disease progressed, his paintings evolved too. And even though he lost the ability to talk or write before his death in 2007, his artwork continued to feature themes from his youth, offering comfort to his family and a fascinating look into the brain of someone with a degenerative and still-mysterious disease.
"It is a known phenomenon that folks can find artistic abilities that had been previously unknown when they get Alzheimer's and other kinds of dementia," says Daniel Potts, who is a neurologist at the University of Alabama School of Medicine and president of Cognitive Dynamics, a foundation that aims to improve the quality of life for people with cognitive impairments. For his father, he says, "this creative energy and newfound talent shored up his sense of self-worth and his human dignity."
By studying works of art like Potts' that emerge from different types of dementia, scientists have begun to map the brain regions that interact to either inspire or inhibit the creation of art.
Patients with a category of brain degeneration called frontotemporal dementia, or FTD, have been particularly illuminating. Here, damage to the front and sides of the brain tend to interfere with sources of personality, behavior and language. As a result, personality changes can be drastic, trending toward the obsessive and meticulous.
People with FTD often develop artistic talents only after the disease strikes, Chatterjee says. Their art usually involves concrete and realistic themes, and they often produce the same images over and over, with small variations.
The late University of British Columbia scientist Anne Adams, for one, started to paint only after the onset of a type of FTD that attacked the language networks in her brain. As her speech disappeared, her artistic creativity flourished.
She became fascinated with French composer Maurice Ravel, who had suffered from the same disease. And she produced a painting called "Unraveling Boléro," which attempted, in a compulsively detailed and organized way, to translate the elements of Ravel's music into visual form. A later work, called "pi," mapped a matrix of colored squares onto the first 1,471 digits of pi.
Adams offered a rare opportunity: It so happened there were images on record of her brain before and after the onset of FTD. After analyzing both sets, UC San Francisco neurologist Bruce Miller and colleagues found evidence that degeneration in the front of Adams' brain may have freed circuits in the back of the brain that allowed her to create.
The study, published in the journal Brain in 2008, also suggested that her brain remodeled itself as the disease progressed. "This shows how plastic our brain is, even in the setting of a slow degenerative disease," Miller says. "If you permanently turn off language circuits, you may have increased activity in other parts."
The theory is supported by some experimental work and by cases of autistic savants, Miller says: He once worked with a young boy named Dane who started spontaneously and prolifically drawing horses at age 2.
"These images came out of his brain directly onto paper," Miller says, in what he suspects is a similar process to what's happening in artists with FTD. "There are these visual parts of the brain that for most of us are turned off most of the time. Whatever disease it is, whether FTD or autistic savants, there is this release that enhances the visual processes — and these images come out."
In cases of Alzheimer's, people follow a different artistic pattern, Miller adds. Degeneration in this disease strikes in the back of the brain, leading to a steady progression from more realistic to more abstract. Faces become distorted. Attention to shape and form morph into a greater emphasis on color.
Brain-damaging strokes like the one Sherwood suffered offer still other insights into the nature of creativity.
Chatterjee and colleagues studied three artists, including Sherwood, who had suffered strokes, and found that the paintings of each artist were more abstract, more distorted and less realistic after the event than before. All three also used more vibrant colors and looser brush strokes.
The damage was on the left side of the brain in two patients, and on the right side in the third. That fact, along with other lines of evidence, helps overthrow some widely held notions on the roots of creativity. Contrary to popular belief — to say nothing of scads of books that have "right brain" in the title — it appears that the right hemisphere is not the only side responsible for making people artistic.
"It's really a coordinated effort," Chatterjee says.
As the art that emerges after brain damage continues to offer lessons about the brain, it is also helping patients and families move forward with their lives.
During the progression of Lester Potts' disease, his art shifted from scenes of wildlife, nature and wood grains toward more abstract versions of things that had always mattered to him most.
One of his most poignant paintings near the end of his life included a saw, a high-top boot and a hat on a cross, which evoked stories he had once shared about his own father. When asked about the image, Lester cried. Though he could no longer speak, he was able to show his loved ones that a core part of him was still in there somewhere.
"We feel he created an abstract representation of something that made him feel good," Daniel Potts says. "It tied him back to a familiar place in his sea of confusion."
Photos: The artistic expressions born of brain disorders