A 25-year-old man who had barely emerged from a coma after a severe brain injury regained full consciousness after doctors used a pioneering ultrasound technique to “jump-start” his brain, scientists have revealed. Previously the only way to attempt this was to put electrodes directly into the brain, an operation the scientists described as “risky”. But using ultrasound enabled them to apparently achieve the same result without the need for surgery in what is believed to…