( CNN ) -- When the body is totally inert , the brain can still be busy . Even in a coma , brain imaging technology has shown , some people 's brains show blood flow patterns that indicate something is going on inside their heads , although it 's not necessarily indicative of awareness . Doctors say they have observed `` significant brain activity '' in former Israeli Prime Minister Ariel Sharon . They are basing this statement on the results of experiments done with functional magnetic resonance imaging , or fMRI , showing that Sharon 's brain behaves differently when he is presented with familiar sounds and pictures than with unfamiliar stimuli . `` It suggests the brain has the capability to react , '' said Dr. Fatta Nahab , neuroscientist at the University of Miami , who is not involved in Sharon 's care . `` What that means in terms of long-term outcomes is indeterminate . '' FMRI lets scientists see changes in blood flow in the brain , which is associated with neuronal activity . It does not measure the actual activity , but can provide clues that some areas are still functional . How such results should be interpreted , and if there 's any connection to a potential recovery , is not known . Doctors compared Sharon 's brain responses when he viewed photos of random houses to when he was shown a photo of his own house . They observed a different response in the brain in conjunction with the familiar place than for the other images . Sharon , 84 , also showed distinct brain activity patterns when his family members spoke to him , compared to when their voices were distorted so they were no longer familiar and sounded like gibberish . The brain response for a family member 's voice was in `` the correct location '' for when a cognitively normal person hears familiar people speaking , said Dr. Ilan Shelef , head of Medical Imaging at Soroka University Medical Center , who was involved in the fMRI tests but is not Sharon 's attending physician . Such results suggest there may be some higher processing of information going on , and that areas of the brain important for processing complex stimuli are still functioning , said Dr. Keith L. Black , chairman and professor in the department of neurosurgery at Cedars-Sinai Medical Center , who is not involved in Sharon 's care . It is not proof that Sharon is conscious of the familiar sounds and images , and recognizing them as a fully healthy person would , he said . Because doctors had not given these tests to Sharon previously , it 's unclear whether this represents an improvement . CNN has reported since 2006 that Sharon has been in a coma since suffering a massive stroke that year . The longer a person is in a coma , the less likely he or she is to recover , Nahab said . Shelef said that Sharon is not in a coma or vegetative state , and is somewhere between a coma and consciousness . He sleeps , wakes up , eats and swallows on his own , and his eyes open and close , Shelef said . Shelef declined to comment on Sharon 's general health . There is a continuum between brain death and normal awareness that patients such as Sharon fall into , Black said . The fMRI results suggest he is not brain dead , because areas above the brain stem are showing activity . There are also patients who are `` locked-in , '' and are totally aware of the sights and sounds around them , but can not move or speak . Brain-controlled devices may help paralyzed people . For clinical purposes , it appears that Sharon is in a coma , Black said . `` We have seen patients make remarkable improvements after being in a coma for a long time , but the best prognostic indicator is how one does over time , '' Black said . `` Most improvement will occur within the first one to two years . '' As Sharon has been in a coma for seven years , the fMRI evidence is positive , but it would be unusual for him to start talking , for example , given how long he has stayed in this state , Black said . The scientists have likely gotten these new results because , even when a person is in a coma , `` parts of the nervous system that are still functioning are capable of learning and capable of changing their activity patterns , '' said Dr. Daniel Hanley , professor of neurology , neurosurgery and anesthesia at the Johns Hopkins University School of Medicine , who is not involved with Sharon 's care . It 's a phenomenon that has been studied and described before , he said . `` Even with severe brain injury , some qualities of the human existence are preserved and we should always treat patients with dignity , '' Hanley said . But it 's unclear what such brain activity patterns would mean for a patient 's future . `` We do n't understand how these small changes in function are linked to recovery , '' he said . If the same fMRI tests are repeated six months and nine months from now to compare activity levels , that would provide some indication of whether Sharon is headed in a positive direction , Black said . `` What you really want to know : Is he improving , and can you extrapolate that improvement out over some period of time to predict how well he 's going to ultimately improve to ? '' he said . Comatose Sharon moves home for weekend . CNN 's Elizabeth Cohen and William Hudson contributed to this report .
It 's not clear how fMRI results contribute to patient 's recovery from a coma . There is a continuum between brain activity and normal awareness . Most improvement in a patient in a coma occurs within one to two weeks .