18 December 2013

Vegetative patients react to photos of loved ones

Researchers from Tel Aviv University found that the brains of patients in a vegetative state emotionally react to photographs of people they know personally.

Using functional magnetic resonance imaging (fMRI), Dr Haggai Sharon and Dr Yotam Pasternak of Tel Aviv University's Functional Brain Centre and Sackler Faculty of Medicine and the Tel Aviv Sourasky Medical Centre have shown that the brains of patients in a vegetative state emotionally react to photographs of people they know personally as though they recognise them.

Personal emotional experiences

For many years, patients in a vegetative state were believed to have no awareness of self or environment. But in recent years, doctors have made use of fMRI to examine brain activity in such patients. They have found that some patients in a vegetative state can perform complex cognitive tasks on command, like imagining a physical activity such as playing tennis, or, in one case, even answering yes-or-no questions. But these cases are rare and don’t provide any indication as to whether patients are having personal emotional experiences in such a state.

To gain insight into "what it feels like to be in a vegetative state", the researchers worked with four patients in a persistent (defined as "month-long") or permanent (persisting for more than three months) vegetative state. They showed them photographs of people they did and did not personally know, then gauged the patients' reactions using fMRI, which measures blood flow in the brain to detect areas of neurological activity in real time. In response to all the photographs, a region specific to facial recognition was activated in the patients' brains, indicating that their brains had correctly identified that they were looking at faces.

Complex visual information

But in response to the photographs of close family members and friends, brain regions involved in emotional significance and autobiographical information were also activated in the patients' brains. In other words, the patients reacted with activations of brain centres involved in processing emotion, as though they knew the people in the photographs. The results suggest patients in a vegetative state can register and categorize complex visual information and connect it to memories – a groundbreaking finding.

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". A second patient, a 23-year-old woman, exhibited activity just in the emotion-specific brain regions. (Significantly, both patients woke up within two months of the tests. They did not remember being in a vegetative state.)


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