After 40 years it has become a tired truism that anyone old enough to remember the assassination of President John F. Kennedy can remember clearly where they were and what they were doing when they first heard the news from Dallas.

For Dr. Robert G. Grossman, this classic "flashbulb" memory is not just a vivid personal recollection. It is one of acute professional and historical significance.

On Nov. 22, 1963, Grossman was a 30-year-old neurosurgeon in Dallas. He had been on the staff at Parkland Hospital for just five months when a telephone call — which he and his colleagues at first suspected was a particularly bad joke — summoned them to Parkland's Trauma Room 1. Kennedy, they were told, had been shot.

In the decades since, Grossman has rarely spoken about what he saw in that room. He never wrote down his recollections. And to his surprise, the Warren Commission, which investigated the assassination, never called him to add his testimony to that of others who were there.

Grossman is 70 now, and chairman of neurosurgery at Baylor College of Medicine in Houston. In the interest of history and medicine, he has finally shared his recollections as part of a series of articles in the journal Neurosurgery exploring the "neuroforensics" of the Kennedy assassination.

The articles were co-written with Daniel Sullivan and Rodrick Faccio, both of the Keck School of Medicine at the University of Southern California; and Dr. Michael L. Levy, of Children's Hospital in San Diego. The first part, published this month, includes Grossman's memories of the events; the next two parts will correlate the trauma-room account with autopsy reports, eyewitness accounts and ballistic evidence.

"The goal of this series of reports," the authors say, "is to establish a reasonable hypothesis regarding the pathological mechanisms that killed President Kennedy."

Grossman, father of three and grandfather of eight, conceded in a recent telephone interview with The Baltimore Sun, that memory "is a very tricky thing.'

Henow regrets his failure to record his observations at the time. "I was just too shocked," he says. "Many of the people who were there wanted to put it behind them. It was a horrible experience, and I didn't think I could really add anything."

He is nevertheless confident about his recollections. "I think something like that is so dramatic that the things you remember, you remember accurately," he says.