9th November 2015

Fastest ever brain-computer interface for spelling

Researchers in China have achieved high-speed spelling with a noninvasive brain-computer interface.

Brain–computer interfaces (BCI) are a relatively new and emerging technology allowing direct communication between the brain and an external device. They are used for assisting, augmenting, or repairing cognitive or sensory-motor functions. Research on BCIs began in the 1970s and the first neuroprosthetic devices implanted in humans appeared in the mid-1990s.

The past 20 years have seen major progress in BCIs. However, they are still limited by low communication rates, caused by interference from spontaneous electroencephalography (EEG) signals. Now, a team of researchers from Tsinghua University in China, State Key Laboratory Integrated Optoelectronics, Institute of Semiconductors (IOS), and the Chinese Academy of Sciences have developed a greatly improved system. Their EEG-based BCI speller can achieve information transfer rates (ITRs) of 60 characters (∼12 words) per minute, by far the highest ever reported in BCI spellers for either noninvasive or invasive methods. In some of the tests, they reached up to 5.32 bits per second. For comparison, most other systems in recent years have been at 1 or 2 ITRs.

According to the researchers, they achieved this via an extremely high consistency of frequency and phase between the visual flickering signals and the elicited single-trial steady-state visual evoked potentials. Specifically, they developed a new joint frequency-phase modulation (JFPM) method to tag 40 characters with 0.5-seconds-long flickering signals, and created a user-specific target identification algorithm using individual calibration data. A paper describing this breakthrough appears in the 3rd November edition of the journal Proceedings of the National Academy of Sciences (PNAS).

In the not-too-distant future, this kind of technology could be applied to other uses, besides medicine. For example, it could be incorporated into smartphones and other consumer electronics to allow texting, typing or other on-screen actions by thought power alone. A partnership between the Japanese government and private sector aims to achieve this by 2020. With continued progress in the speed of BCIs, a new form of "virtual telepathy" could emerge within a few decades.

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