Have you ever wished changing your music was as easy as glancing at a shuffle icon on your screen? Chances are if you’re on this website the answer is an emphatic yes, and according to recent research by the University of Malta you may be able to do so sooner than you think.The team of scientists from Malta are focused on improving quality-of-life for severely paralyzed or otherwise motor-impaired individuals, as is so often the case in translational applications of brain-computer interfaces. Key to any kind of computer interface for someone who has severe motor deficiencies is one that does not involve body movement, so BCI’s are an ideal tool for the job.
Essentially, the system exploits two key details of the nervous system: the special nerves that innervate muscles in the eyes, and the brain’s way of processing vision. Users wear an EEG cap with electrodes that record activity from the visual cortex, and simply look at whatever icon corresponds to the action they want and the system makes it happen. But how does it actually work? To explain that, it helps to have a little background on the nervous system.
Many people become paralyzed by suffering an injury to the spine, cutting off the natural flow of signal from the brain down through the spine and out to muscles. Fortunately a separate set of nerves go directly from the brain to a few select parts of the body (known as ‘cranial nerves’), bypassing any damage to the spinal column entirely; the Oculomotor nerve, which controls eye movements, is one of these. Thus, even individuals who have whole body paralysis can usually still move their eyes to look at an icon on a screen.
When an image (such as a play button on a screen) gets received by the eye, the signal is sent to the visual cortex of the brain for processing. Different brain cells process different simple parts of the image, like motion and colour, and pass that information up to different areas that do more complicated processing, like identifying shapes. As you could imagine, there are many basic cells that are active when seeing an image (any image) and not very active when no image is present.
To exploit this, researchers caused different icons on the screen that a user is looking at to flash at different frequencies. Neurons in the visual cortex respond very quickly to changing signals from the eye (much faster than humans are consciously aware of), and so looking directly at any one icon causes the brain to ‘strobe’ at the same frequency as that icon. EEG electrodes pick up this strobing brain activity, check it against the frequency of all the icons, and decide which icon the user is looking at and therefore what action to perform (stop, skip, shuffle, and so on).
While a BCI-powered music player is fairly remarkable in and of itself, there is no reason why a nearly identical system couldn’t control anything that can be operated by icons on a screen or monitor, and virtually everything in the modern world falls in this category.
Current commercial BCI headsets, such as the Neurosky MindWave and Emotiv EPOC, don’t support electrodes on the back of the skull (area of the visual cortex), preferring to focus on frontal areas that are more associated with complex thought. Success of research like this may change that, giving us a powerful new tool for interacting with our computers and our world.
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