Studies find brain cells grow with stimulation

BERKELEY, Calif. — Peek into the University of California-Berkeley’s Wheeler Auditorium during Integrative Biology 131 and you might catch professor Marion Diamond as she turns her palms toward herself, fingertips pointing toward each other. ”Dendrites,” she would announce, spreading her slender fingers to represent the spiny branches that jut out from nerve cell endings.

Or, she might raise her hands on either side of her head, elbows bent, and curve her fingers like the sloping beak of a crane to mimic fallopian tubes.

Diamond has been explaining anatomical ins-and-outs at UC-Berkeley for nearly 40 years. Her curriculum vitae stretches further back to lecturing stints at UC-San Francisco and Cornell University. But it has been at her alma mater that she has amassed an exhaustive string of credentials and awards, including Berkeley’s Outstanding Teaching Award, a Distinguished Teacher’s Award, the CASE California Professor of the Year and National Gold Medalist, and the California Alumni Association’s 1995 Alumna of the Year.

At 71, Diamond emanates a palpable intellectual vigor and passion. In addition to teaching, she has been part of a Berkeley team that for 35 years has tracked environmental effects on the brain. They have uncovered findings about gender differences, immunity, nurturing influences and aging that have upended traditional thought.

”The prevailing view (before the 1950s) was essentially you were dealt a hand of nerve cells, and they didn’t change after you developed,” Diamond says. ”Well, it’s amazing that it was sort of the lay thought for so long, when you look at what scientists were saying.”

Scientists had noted, for example, that domestic rabbits had smaller brains than wild rabbits. An early 20th-century neurologist recommended cerebral exercises to keep the brain active. And when Diamond’s team was forming in the 1950s, a college psychologist who let his rats free in his home discovered his pets could run a maze better than caged animals. Trial runs bore him out.

The Berkeley team created enriched, standard and isolated conditions for their rat colonies to compare brain development. Cross-sections revealed rats with toys and good food had the highest brain cell.

”Looking back, of course, (it) is so simple,” Diamond says. ”Nerve cells are designed to receive stimuli, and if you stimulate them, they grow their branches. If you cut off the stimulation, you lose the branches.”

Decline is inevitable, and actually starts at age 10 with the natural ”pruning” or removal of excess branches, but stimulation can stave off the rate of decline. The work proved that nurture influenced nature. ”That’s why our work was sort of revolutionary 30 years ago.”

That this resolutely elegant woman makes her living from rodents seems an unlikely proposition. But watch her handle her favorite teaching aid, an alcohol-preserved brain in an unabashedly floral hatbox, and her fascination is unmistakable. (Department personnel who ”thought the brain deserved more dignity” gave her the receptacle.)

She keenly remembers the first time she viewed the wrinkled gray matter of the human brain as a 14-year-old. ”I looked at it and said, ‘That’s what can think,’ ” she says in awe. ”I mean, you talk about a tropism. There was that instant attraction.” Her obsession has never flagged. Even years later, she would stare at people’s skulls. ”I would think of their heads and what was going on in there.”

Diamond had another reason to pursue the sciences. Lupus, an autoimmune deficiency, killed two of her siblings and a niece and contributed to her daughter’s joint disease. ”I promised my sister when she died — I was 19, she was 26 — I said someday I’ll learn something about this, but I got to do it my own way. It’s got to come through the brain.”

She has recently fulfilled her promise to her sister by guiding a graduate student’s seven-year study, which reversed an immune deficiency by grafting a thymus gland onto the brain. Brain Research just published the article.