Some 25,000 people in the United States alone live in some form of a vegetative state. While experiments suggest some of these people are still capable of thought, they're unable to speak or make conscious movements. Many people in these conditions never wake—especially after long periods of time.
But as Michael Price reports for Science, a new therapy is offering cautious hope to friends and families with unresponsive loved ones. With the test of a new treatment, researchers are taking the first tentative steps toward the possibility of awakening people in a vegetative state. They published their results this week in the journal Current Biology.
The new study chronicles the use of the treatment on a French man who suffered a traumatic brain injury in a car crash 15 years ago, reports Hannah Devlin for the Guardian. Neuroscientists inserted a small implant into the man's necks to stimulate his vagus nerve—a long nerve traveling directly into the brainstem and connects to the thalamus, which is thought to be critical for alertness.
This implant was used to gently but directly stimulate the man's vagus nerve over the course of months. The results were small but dramatic.
Soon, the man's eyes opened more often, and he seemed to be able to move them consciously in response to instructions, reports Anil Ananthaswamy for New Scientist. He appeared to move his cheek in response to instructions to smile, and even formed tears in his eyes when his favorite music was played for him. He also demonstrated increased brain wave activity. Overall, the man's score on the "Coma Recovery Scale" increased from 5 to 10 (out of 23 total).
What could be causing this sudden improvement in brain activity? The stimulation of the vagus nerve could in effect be giving the thalamus a volume boost in the brain, reports Price. Scientists theorize that vegetative states can be caused by damaged connections between the thalamus and other regions of the brain, so a more forceful thalamus could overcome this damage to stimulate consciousness in other brain regions.
Though excited by these results, other neuroscientists remain cautious about how this therapy should be used, reports Ryan Mandelbaum for Gizmodo. The nature of a brain injury could make it much less effective for some people than others, and scientists should be careful to stress that this man became only minimally conscious, not fully conscious, even after months of daily treatment.