IMAGINE being able to manipulate images on a screen by thought alone. That's the tantalising prospect raised by a brain-machine interface that lets you control which of two competing images you can see on a screen.
Moran Cerf at the California Institute of Technology, Pasadena, and colleagues recruited 12 volunteers who had electrodes implanted in their brains to record epileptic seizures. That meant the team could record activity in the normally inaccessible medial temporal lobe. The MTL houses the hippocampus and amygdala, which are involved in memory and emotions.
Cerf first talked to each person about their interests and recent experiences - the concepts making up their recent memories.
His team then created a database of images to correspond to those concepts, such as a picture of the Eiffel Tower for a person who recently visited Paris, France. Next each person had their brain activity recorded as they looked at 100 of those pictures six times. The team could then identify the individual neurons that fired in response to each image.
The team then chose two images for each person that caused firing in different individual neurons. The two pictures were superimposed, and the person asked to control the strength of each image by focusing on the concepts related to each picture. A brain-machine interface translated the neural activity related to an image so that it was portrayed more or less vividly on the screen. In 70 per cent of tests, volunteers were able to bring one image to the fore (Nature, DOI: 10.1038/nature09510).
Although humans and monkeys can already control the movement of a robotic arm via the brain's motor cortex, this is the first time anyone has been able to tap into the neurons associated with individual concepts.
Fabien Lotte at the Institute for Infocomm Research in Singapore says the findings could be useful clinically. "A paralysed person could increase the activity in a neuron that corresponds to the person they want to call, for example," Lotte says.
If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.