London: For several years, patients in a vegetative state were believed to have no awareness of self or environment.
New research, using functional magnetic resonance imaging (fMRI), has shown that brains of patients in a vegetative state emotionally react to photographs of people they know personally as though they recognise them.
"We showed that patients in a vegetative state can react differently to different stimuli in the environment depending on their emotional value. It's not a generic thing; it's personal and autobiographical. We engaged the person, the individual, inside the patient," said Haggai Sharon and Yotam Pasternak of Tel Aviv University's Functional Brain Centre and Sackler Faculty of Medicine and the Tel Aviv Sourasky Medical Centre.
To gain insight into what it feels like to be in a vegetative state, the researchers worked with four patients in a persistent vegetative state. They showed them photographs of people they did and did not personally know.
In response to the photographs of close family members and friends, patients reacted with activations of brain centres involved in processing emotion, as though they knew the people in the photographs.
The results suggested that patients in a vegetative state have the ability to register and categorise complex visual information and connect it to memories.
However, the researchers could not be sure if the patients were conscious of their emotions or just reacting spontaneously. So they then verbally asked the patients to imagine their parents' faces.
Surprisingly, one patient, a 60-year-old kindergarten teacher who was hit by a car while crossing the street, exhibited complex brain activity in the face- and emotion-specific brain regions, identical to brain activity seen in healthy people.
The researchers say her response is the strongest evidence yet that vegetative-state patients can be "emotionally aware".
The findings of the study have been published in PLOS ONE.
