People are medically defined as vegetative when they have no recognisable behavioural responses to external stimuli, says Riganello. "Generally it is thought that vegetative patients are isolated from the external world, but maybe this is incorrect."
Interestingly, heartbeat patterns detected in people listening to Boccherini's music in previous studies indicated that the listeners were becoming relaxed. Riganello suggests that listening to music may have caused "some relaxation" in the vegetative patients.
He believes this reaction originates from the lower regions of the brain, such as the limbic and paralimbic system. These are known to control emotion and autonomic responses and "may remain active after extensive brain damage".
"It's a nice paper," says Ashley Craig, a rehabilitation neuroscientist at the University of Sydney, Australia, who was not involved in the study. He points out, however, that it doesn't show the vegetative people feel emotions as healthy people do. Although their basic, automatic brain functions are working, "that's very different" from the higher cognitive processes required to be conscious and feel emotions, he says.
Alan Harvey at the University of Western Australia in Crawley agrees, but finds it very interesting that "music has this way of affecting neural systems that process emotion even in the absence of conscious thought".