New frame of mind as thoughts control on-screen images
A new attempt to link brains to machines has enabled volunteers to make screen images appear and fade away simply by thinking.
The experiment, conducted in the US, involved 12 epilepsy patients surgically implanted with brain electrodes to locate the source of their seizures.
Neuroscientists used the electrodes to connect individual neurons deep inside the brain to images on a screen.
With practice, the volunteers were able to control the appearance of "hybrid" images consisting of one picture superimposed on another.
On cue they could quickly make a particular image, such as Marilyn Monroe or former US president George Bush, "fade in" or "fade out".
During the tests, patients worked out their own strategies for conjuring up the right images.
Some simply thought of the picture, while others repeated the name of the image out loud or stared at a particular aspect of the image.
All the participants quickly mastered the task and were successful in around 70pc of trials.
Dr Moran Cerf, from the California Institute of Technology (Caltech), who worked on the research reported yesterday in the journal 'Nature', said: "The patients clearly found this task to be incredibly fun as they started to feel that they controlled things in the environment purely with their thought.
"They were highly enthusiastic to try new things and see the boundaries of 'thoughts' that still allow them to activate things in the environment."
Scientists have previously used the activity of neurons in the brain to control a cursor on a computer screen.
This was also achieved by the Caltech team. By thinking of individual images, the volunteers were able to move a cursor up and down and even play a computer game.
But Dr Cerf said the team wanted to go a step further and "tap into the competition for attention between thoughts that race through our minds".
And the "hybrid" images experiment seems to have done just that.