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