Brain waves can have a direct influence on a person's behaviour, say researchers after an experiment found that people can be made to move in slow motion by boosting one type of brain wave .

"At last we have some direct experimental proof that brain waves influence behaviour in humans, in this case how fast a movement is performed," said Peter Brown of University College London (UCL).

In this study, researchers injected a small electrical current into the brain through the scalps of 14 people while the participants manipulated the position of a spot on a computer screen as quickly as they could with a joystick.

The electrical current used increased normal beta activity, a wave that earlier studies linked to sustained muscle activities, such as holding a book. Beta activity drops before people make a move.

Unlike most previous work, which used constant brain stimulation, the new study employed an oscillating current, more like that underlying normal brain activity. As a result, people's fastest times on the computer task were 10 percent slower.

"If we know what patterns of brain activity slow voluntary movement, then we can try and boost these patterns in conditions like chorea and dystonia, where there is excessive and uncontrolled movement," Brown said.

"Conversely, we can try and suppress beta activity in conditions like Parkinson's disease typified by slow movement." "The implication is that it is not just how active brain cells are that is important, but also how they couple their activity into patterns like beta activity."