Scientists may have pinpointed the area of the brain that malfunctions in people who have a stammer.

They think the problem for some sufferers may lie with cells which link two areas in the left hemisphere of the brain.

Brain scans revealed that when the two areas - already thought to play a role in language - tried to communicate with each other, the activity was "mistimed".

However, it is not known whether these brain differences are the cause of the condition - or simply changes experienced as a result of living with it for years.

The question is how you now change the structure of the brain?

Dr Trudy Stewart, St James' Hospital, Leeds

However, it may offer scientists a chance to check on the progress of their anti-stammering therapies.

The precise origins of stuttering are still unknown - there are many theories, and it is suspected there is a genetic root to some cases.

However, the research, from Hamburg University, is likely to complement other studies which have noticed "structural" differences in the brains of people with the condition.

The research team studied 15 people with varying degrees of stammering.

They used a type of scan called diffusion tensor imaging to create a detailed picture of what was going on in their brains.

In particular, they were able to estimate the ability of the brain to transmit signals through an area called the Rolandic operculum.

In non-stammering control subjects, there was more white matter in this area, suggesting that communication through this region would be easier.

Practical help

However, an expert in speech and language therapy said that it would not immediately influence the way she worked.

Dr Trudy Stewart, who works at St James' University Hospital in Leeds, said that more work was needed before the finding could be of practical benefit.

She said: "The question is how you now change the structure of the brain - there is certainly no way of doing so at the moment."

She said that one way the scans could assist might be to help in the diagnosis of stammering, or to chart the progress of patients under therapy.

If children who stammer receive help early enough, they can be completely cured with conventional therapy.

Adults with the problem may never be cured - even with extensive voice and lifestyle training - although the problem can be lessened greatly.