Doctors at Beersheba's Soroka Medical Center said that "significant brain activity was detected during tests" performed on 84-year-old Sharon.
This activity was detected during each of the MRI scans and in the "matching" areas of the brain, Ynetnews quoted doctors as saying.
Sharon suffered a stroke seven years ago in 2006. Since then, he has been in a vegetative state, connected to a respirator.
Sharon was tested at Soroka with a Functional magnetic resonance imaging (FMRI) machine on Thursday.
During the two-hour examination, Sharon was shown photos of family members and doctors played a recording of his son Gilad's voice in order to check if and to what extent his brain responds to external stimulation.
The tests' findings showed "significant" brain activity.
Additional tests were performed to determine Sharon's awareness to his surroundings, but they did not give a clear indication that he is in fact aware of his surroundings.
"The test was routine, but the results not entirely so," Sharon's former aide Raanan Gissin said. "There was some kind of positive indication."
While the latest development did not mean Sharon was likely to fully regain consciousness, doctors said the signs were "encouraging".
Sharon was admitted to the renowned Hadassah hospital in Jerusalem after suffering the massive stroke. He was moved to the Chaim Sheba Medical Center at Tel Hashomer and has remained there in serious but stable condition ever since.
Sharon was elected prime minister in 2001 and served until he suffered a stroke in 2006.
