At the time, the scientists wondered if such results could be repeated, or if their success was just a one-off. They have now done it two more times.

In the 2016 case, a team led by Prof. Martin Monti utilized a coffee cup saucer-sized device to deliver stimulating pulses of low-intensity focused ultrasound to the thalamus of a 25 year-old coma patient. The thalamus acts as the brain's central processing hub, and it is typically weakened in coma patients.

After receiving the treatment, the patient improved dramatically. Whereas he previously only showed minimal signs of consciousness, he was now fully awake, able to understand questions, and capable of responding by shaking or nodding his head. At the time, though, the researchers wondered if they might have just gotten lucky – they may have treated the patient at the same time that he was coming out of the coma on his own, or his brain might have been uniquely receptive to the treatment.

Now, though, Monti and colleagues have announced that they recently experienced two more successes.

One case involved a 56 year-old man who had been in a minimally conscious state for over 14 months since suffering a stroke. After his first ultrasound treatment, he was consistently able to drop or grasp a ball when told to do so, and to look toward either of two photographs of relatives when their names were mentioned. After the second treatment, he was additionally able to raise a bottle to his mouth, use a pen and paper, and to verbally communicate.