Doctors on Tuesday sought to understand why a brain-damaged firefighter snapped to attention after nearly a decade of sitting silently in a wheelchair and watching television at his nursing home.

Firefighter Donald Herbert, 43, abruptly turned talkative and lucid to the delight of family and friends who visited him on Saturday after he asked staff at the facility where his wife, Linda, was.

A news conference on Herbert’s condition was scheduled on Wednesday, said JoAnn Cavanaugh, spokesperson for the Catholic Health System, which operates the nursing home near Buffalo, New York, where he has lived for the past 7-1/2 years.

Herbert spent 14 hours chatting and catching up on news about his wife, four sons, friends and former firefighting colleagues. He then went into a deep sleep for 30 hours.

Herbert has maintained an improved condition but not to the extent of Saturday’s stunning revival, Cavanaugh said.

Buried under flaming debris while searching a Buffalo apartment building in December 1995, Herbert went without oxygen for about six minutes before being rescued.

He lapsed into a coma for more than two months. When Herbert came out of it, he had lost his sight, his speech was halting and slurred, and he did not recognize loved ones.

“We can tell you he did recognize several family members and friends and did call them by name,” Simon Manka, his uncle, said in a handwritten statement issued on behalf of the family.