Dr. Olney, 56, met with a visitor last week in a wide-ranging interview conducted partly in his old office, where so many people got long hours of counseling after learning they had A.L.S. that they call it the kiss-and-cry room. He was joined by his wife, Paula, and by Dr. Catherine Lomen-Hoerth, a neurologist he trained at the center, who has succeeded him as director.

The causes of A.L.S. are still largely unknown; about 10 percent of cases appear to be linked to genetic flaws, while the other 90 percent are a persistent mystery. In an exchange of e-mail messages before the interview, Dr. Olney explained that he was first drawn to the disease as a field of study after becoming a neurologist.

"I found out that the daughter of my favorite teacher in junior high died from A.L.S.," he said. Having also trained as a psychiatrist, he said he was "much more comfortable than most neurologists in relating to patients with fatal disease."

He also liked the fact that people with A.L.S. remained mentally sharp. And, he said, in the early 1990's, "advances in molecular biology suggested that A.L.S. might become very treatable during my career."

Then he got the disease himself. Dr. Olney began noticing problems in July 2003: his right leg was becoming a little stiff, and his movement and coordination were slightly impaired. An extensive neurological evaluation turned up a protruding disk that compressed his spinal cord, and so he underwent back surgery in September of that year. For a month afterward, he seemed to be getting better, but by November, "I was obviously getting worse," he wrote. "The possibility of A.L.S. was raised, and was my expectation, as I underwent another round of testing."