A seriously injured man has had his speech restored by an electronic implant placed deep inside his brain.

The 38-year-old man had suffered serious brain trauma six years ago and was described as being in a 'minimally conscious state', according to a paper published in Nature. Scientists implanted an electrode to stimulate his central thalamus, which handles motor control, arousal and in relaying sensory signals to the cerebral cortex.

After the operation the man was able name objects on request, make precise hand gestures, and chew food without the aid of a feeding tube. However he is unable to perform many physical tasks because of muscle degradation.

Nicholas Schiff of Weill Cornell Medical College in New York and his team performed the ten-hour operation to install the implant, which is powered by a portable battery pack.

"There will be a subset of patients who are responsive to this approach," said Schiff.

"Not every patient in a minimally conscious state will fit this profile," Schiff added, "and it is difficult for neurologists to identify those patients who will show recovery."

However, it is estimated that there are as many as 400,000 people who could benefit from the treatment.

"The report does not suggest that deep-brain stimulation [DBS] 'cures' the minimally conscious state," said Paul Matthews, a clinical neuroscientist at Imperial College, London.

"Although based on a study of only a single patient, it suggests that DBS may be adapted to benefit at least some patients in the minimally conscious state. And it emphasises that improvements can be made by patients even long after an injury."