Scientists used a brain-computer interface to show how the activity of just a few brain cells can control the display of pictures on a computer screen. The finding sheds light on how single brain cells contribute to attention and conscious thought.
Researchers have been making great progress in developing brain-computer interfaces—devices that let a person's thoughts guide the actions of a computer. This technology can potentially help paralysis patients control prosthetic limbs and communicate.
A team of scientists led by Dr. Itzhak Fried at the University of California, Los Angeles, used a brain-computer interface to investigate whether you can consciously control computer images by changing the activity of your brain cells. The study was funded in part by NIH's National Institute of Neurological Disorders and Stroke (NINDS) and National Institute of Mental Health (NIMH).
The scientists recruited 12 patients with drug-resistant epilepsy. As part of their treatment, these patients had wires connected to their brains to locate their seizure activity. The wires can also send information from the patients' brains to a computer.
In a previous study, the researchers found that individual brain cells respond more strongly to certain images than to others. For example, one brain cell might respond to a picture of Marilyn Monroe, and another to a picture of Michael Jackson.
For this study, the scientists first identified neurons in each person that responded selectively to 4 different images. The patients then played a game that started with a 2-second display of a target image. They were subsequently shown a hybrid image of the target superimposed on 1 of the 3 remaining images. Their task was to focus in on the target image until the other disappeared. The computer monitor updated every tenth of a second to reflect the activity in their brains.
The results appeared in the October 28, 2010, issue of Nature. In nearly 900 total attempts, the patients were able to use their thoughts to control the images they saw on the computer screen 69% of the time—often on the first try.
The researchers found that the subjects succeeded at the task when they increased the activity of cells that preferred the target image and decreased the activity of cells that preferred the non-target image. Other studies have shown that subjects can control the movement of a cursor on a computer screen using thought alone, but the task in this study was much more complex.
"The remarkable aspects of this study are that we can concentrate our attention to make a choice by modulating so few brain cells and that we can learn to control those cells very quickly," says Dr. Debra Babcock, a program director at NINDS.
In addition to improving our understanding of conscious thought processes, these findings may help lead to more sophisticated brain-computer interactions.
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