Using brain signals alone, participants in a new study were able to prompt a computer screen to display the particular image of their choice.
“The subjects were able to use their thoughts to override the images they saw on the computer screen,” said the study’s lead author, Itzhak Fried, M.D., Ph.D., a professor of neurosurgery at the University of California, Los Angeles.
During the research, volunteers’ brains were connected to a computer that showed two overlapping images. Then, by using brain signals transmitted to the computer from a relatively small number of brain cells, the participants were able to force the computer to display one of the images and discard the other.
The study’s participants were 12 epileptics who had tiny wires implanted in their brains to monitor seizure activity. These recordings are commonly used to pinpoint the brain areas responsible for seizures. In this study, the wires were placed in the medial temporal lobe, a region associated with memory and the ability to identify complex images, such as faces.
As their brain signals were transmitted to a computer, the participants looked at two merged pictures on a computer screen, each picture displaying a familiar object, place, person or animal. The researchers then told the volunteers to mentally choose one image and to focus on it until that picture became fully visible and the other image faded away.
Surprisingly, the study only required four cells in the temporal lobe. Previous research has shown that each individual cell in this section of the brain will send out impulses at a higher rate when it prefers a certain image. For example, one particular cell in the temporal lobe might respond to a photograph of Marilyn Monroe, while another might react to Michael Jackson. Both of these celebrity faces were used during the study.
“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,” said Debra Babcock M.D., Ph.D., a program director at the National Institute of Neurological Disorders and Stroke (NINDS).
The study emphasizes the technological leaps being made in brain-computer interface (BCI) development—devices that allow people to direct computers or other instruments through their thoughts. BCIs offer great promise for paralyzed people who would be able to communicate or control prosthetic limbs with the devices.
For this study, however, BCI technology was used as a means to figure out how the brain processes information, and to better understand how thoughts and choices are linked to the shared activity of single brain cells.
This game was played by the group nearly 900 times in all, and the participants were successful at getting the computer to show the target image 70 percent of the time. The volunteers seemed to catch on very quickly and were often successful on their first attempt.
“This is a novel and elegant use of a brain-computer interface to explore how the brain directs attention and makes choices,” said Babcock.
The study is published in in the journal Nature and was funded in part by the National Institute of Neurological Disorders and Stroke (NINDS), and the National Institute of Mental Health (NIMH), both part of NIH.
Source: National Institutes of Health