Throughout your life, your brain literally changes based on everything you learn and experience.
That concept, known as "plasticity," underlies our basic assumptions about learning, memory, early childhood education, even stroke recovery. But it wasn't always accepted.
It can be traced to the work of University of Illinois scientist William T. Greenough, who pioneered the study of brain plasticity and development during his 40-year academic career.
Mr. Greenough, professor emeritus of psychology, died Dec. 18 in Seattle of complications associated with Lewy Body Dementia, a brain disease similar to Parkinson's and Alzheimer's. He was 69.
"Bill Greenough was a towering figure in neuroscience for many years," not just on this campus but around the world, said Neal Cohen, UI professor of psychology, one of many scientists recruited here by Mr. Greenough.
Starting in the late 1960s, Greenough explored the neural basis of learning and memory and the effects of aging, exercise, injury and environmental enrichment on the brain, using rats as his subjects.
His work overcame early views that sensory and motor systems of the brain were largely fixed early in life, showing instead that new synapses formed in response to environmental enrichment and learning, said Cohen, director of the Neuroscience Program once led by Mr. Greenough. Rats in stimulating environments developed more connections than those isolated in cages.
At the time, it was "the world was round vs. flat" kind of argument, said Jeffrey Kleim, a former graduate student under Mr. Greenough and now associate professor of biomedical engineering at Arizona State University.
Other scientists at the time were doing similar work but looked mostly at the effect on behavior or overall brain size, said UI psychology Professor Janice Juraska, a longtime friend and colleague. It was Mr. Greenough who showed that neurons in the brain physically changed at the most basic cellular level, she said.
"When I read the first article about it, I sat in the library and thought, 'This has such political implications,'" said Juraska. "Education, the home environment, everything that happens to a kid is influencing how this is all going to go. It's not predetermined."
At the time the prevailing view was that intelligence was inherited and that "your class sort of represented your potential," she said.
Mr. Greenough's research proved that environment, exercise and training continue to shape the brain throughout life, Cohen said.
He went on to identify the mechanisms and signals that regulate those changes in the brain. His work led to new insights into how those functions can go awry in conditions such as Fragile X syndrome, the most common cause of inherited mental impairment, he said.
Mr. Greenough changed fields from psychiatry to audiology to neurology — anything to do with the nervous system, said Kleim.
Mr. Greenough was born in Seattle but grew up in Gearhart and Seaside, Oregon. He finished his undergraduate degree in psychology from the University of Oregon at age 19, earned a doctorate in psychology at the University of California at Los Angeles and joined the UI faculty just before his 24th birthday.
He was often referred to as the "boy wonder," said Juraska, who described him as "a vortex of ideas and energy."
"He really was gifted," Kleim said. "People used to have to stop him all the time and say, 'Wait, my brain doesn't work like yours.'" Yet he had an easygoing teaching style that "masked this mental powerhouse that he was," he said.
Still, his passion for his work always came through, as when he'd pace briskly during class or smack the screen with his pointer to emphasize a concept, Cohen said.
Greenough took a special interest in the undergraduate students in his lab and won teaching awards.
"He liked bringing them to a place where they could explore things on their own," Juraska said. "Not many professors even think of it that way."
By the time he retired in 2009, Mr. Greenough held a Swanlund Endowed Chair and appointments in psychology, psychiatry, and cell and developmental biology. He served as director of the Neuroscience Program and the Center for Advanced Study.
He played a key role in the establishment of the UI's Beckman Institute for Advanced Science and Technology, recruiting top scientists who shared its mission of interdisciplinary, collaborative research. He was one of the first two associate directors and led its biological intelligence research theme.
He was active on the national front, lobbying Congress to invest money in specific research areas and taking leadership roles in major scientific organizations, Kleim said. He was named a fellow of the American Association for the Advancement of Science and the American Academy of Arts and Sciences and was elected to the National Academy of Sciences in 1992.
He was also a passionate sailor and loved to ski.
The cruel irony of the disease that led to Mr. Greenough's death saddens his colleagues.
"He was very aware of what this was," Juraska said. "For a while he was hopeful he could outsmart it, but it wasn't so. It was tragic."
He is survived by his mother, Maryon Greenough; sister, Mary Kerwin; brother, Thomas Greenough; daughter, Jennifer Greenough; son-in-law, Jorge Jimenez; and two grandchildren, Alejandro and Mateo Greenough.