The patients watched a series of 5- to 10-second film clips, some from popular television shows like “Seinfeld” and others depicting animals or landmarks like the Eiffel Tower. The researchers recorded the firing activity of about 100 neurons per person; the recorded neurons were concentrated in and around the hippocampus, a sliver of tissue deep in the brain known to be critical to forming memories.

In each person, the researchers identified single cells that became highly active during some videos and quiet during others. More than half the recorded cells hummed with activity in response to at least one film clip; many of them also responded weakly to others.

After briefly distracting the patients, the researchers then asked them to think about the clips for a minute and to report “what comes to mind.” The patients remembered almost all of the clips. And when they recalled a specific one — say, a clip of Homer Simpson — the same cells that had been active during the Homer clip reignited. In fact, the cells became active a second or two before people were conscious of the memory, which signaled to researchers the memory to come.

“It’s astounding to see this in a single trial; the phenomenon is strong, and we were listening in the right place,” said the senior author, Dr. Itzhak Fried, a professor of neurosurgery at the University of California, Los Angeles, and Tel Aviv University.

His co-authors were Hagar Gelbard-Sagiv, Michal Harel and Rafael Malach of the Weizmann Institute of Science in Israel, and Roy Mukamel, of U.C.L.A.

Dr. Fried said in a phone interview that the single neurons recorded firing most furiously during the film clips were not acting on their own; they were, like all such cells, part of a circuit responding to the videos, including thousands, perhaps millions, of other cells.

In studies of rodents, including a paper that will also appear Friday in the journal Science, neuroscientists have shown that special cells in the hippocampus are sensitive to location, activating when the animal passes a certain spot in a maze. The firing pattern of these cells forms the animals’ spatial memory and can predict which way the animal will turn, even if it makes a wrong move.