Volunteers control screen images by thought alone
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 70% of trials.
Dr Moran Cerf, from the California Institute of Technology (Caltech), who worked on the research reported today in the journal Nature, said: “The patients clearly found this task to be incredibly fun as they started to feel that they control 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”.
The “hybrid” images experiment did just that – by allowing two mingled images to compete for dominance in the brains of the volunteers.
In each session, a participant was asked to “fade in” a “target” image and “fade out” a competing “distractor” image.
Even in cases where the “distractor” image made up 90% of the whole picture, the volunteers were able to seize upon the target in their mind and “pull it back”, said Dr Cerf.
He cited an example where the target and distractor images were former US presidents Bill Clinton and George Bush.
When volunteers “failed” at the task, the picture of George Bush dominated.
“The patient will see George Bush, but they’re supposed to be thinking about Bill Clinton,” said Dr Cerf.
“So they shut off Bush – somehow figuring out how to control the flow of that information in their brain – and make other information appear. The imagery in their brain is stronger than the hybrid image on the screen.”
