Israeli Prime Minister Ariel Sharon at his Jerusalem office Dec. 27, 2005. (Image credit: Kevin Frayer/Pool/Getty Images)

Former Israeli Prime Minister Ariel Sharon, who has been in a vegetative state since a 2006 stroke, might be able to hear and understand, a brain imaging test revealed.

The two-hour test by a team of Israeli and American scientists used functional MRI to gauge Sharon's response to tactile stimulation, photos of his family and the voice of his son.

Functional MRI - or fMRI - measures blood flow as a surrogate for brain activity. And according to a statement from Sharon's medical team, the 84-year-old had "significant brain activity" during the test.

"Information from the external world is being transferred to the appropriate parts of Mr. Sharon's brain," team member Martin Monti, assistant professor of cognitive psychology at the University of California, Los Angeles said in a statement. "However, the evidence does not as clearly indicate whether Mr. Sharon is consciously perceiving this information."

Sharon was put in deep sedation, also known as a medically-induced coma, after suffering a massive stroke Jan. 4, 2006. Although he appears to be awake at times, Sharon never seemed to regain consciousness. A ventilator breathes air into his lungs and a tube delivers essential nutrients to his stomach.

The new brain imaging test used a new "state-of-the-art" MRI machine jointly owned by the Soroka Medical Center in Israel's Beersheba and Ben-Gurion University of the Negev.

"It is important that these new techniques be available in Israel for the large number of patients considered to be in a vegetative state," said Alon Friedman, head of the Zlotowski Center for Neuroscience at Ben-Gurion University of the Negev. "Knowing what sensory channels are intact in these patients is crucial for the family and the treating team to stimulate and interact with them."

The ability to detect consciousness among patients in a vegetative state is controversial. A January 2013 study published in The Lancet challenged earlier findings on the use of electroencephalography to assess awareness, concluding that brain activity seen in vegetative patients could be the result of random chance.

But Sharon's youngest son, Gilad Sharon, has long insisted his father could hear, telling the New York Times in 2011, "When he is awake, he looks at me and moves fingers when I ask him to… I am sure he hears me."

Gilad Sharon said he or a member of his family has visited the former prime minister every day since the stroke, describing in his 2011 book, "Sharon: The Life of a Leader" a dream he had before the devastating stroke.

"In that dream I was with my father in the hospital. He was lying in bed, surrounded by medical staff, and they had all either given up or lost hope and were about to leave, and my father didn't say a thing, but he stared at me with this look, with those green-gray eyes of his, and I knew I would never give up, and that I simply would not leave him," he wrote. "This was a dream I had when my father was healthy and strong and the scenario was completely divorced from reality. I did not tell a soul about the dream at the time, but now I shared it with them and my fear that it was happening now and that I would never be able to forgive myself if we did not fight to the end."