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Matthew McKee/BrainGate Collaboration Matthew McKee/BrainGate Collaboration

We're one step closer to the day when people can control computers with thoughts.

An eclectic team of researchers affiliated with BrainGate, a consortium of neuroscientists, engineers, computer scientists, and mathematicians, have published a study in Nature Medicine that profiles two subjects who control a cursor with their thoughts more deftly than previous systems allowed. Earlier versions of the system allowed subjects to perform such tasks as drinking from a coffee thermos using a robotic arm, or playing simple games. The latest version brings finer control and ease of use. One participant was even able to type at a rate of six words a minute, using software originally developed to help people type type with eye movement.

BrainGate is developing technology for people who have lost use of their limbs. This study's anonymous subjects, referred to as T6 and T7, both suffer from amyotrophic lateral sclerosis (ALS). A year before these tests began, they each had a 4 millimeter-square "neural recording device" surgically implanted in the part of their brain that controls hand function. The sensor intercepts electrical impulses in the brain and translates them into a computer signal that controls an on-screen cursor.

The subjects were asked to perform various tasks, such as navigating a cursor to a target randomly placed on the screen, as T6 does above. This study deployed an updated algorithm that reduced the time lag between thought and cursor movement; it also made the cursor's movement less jittery. T6 told the researchers that with the older software, she essentially had to invent a strategy for moving the cursor. "Afterward, she said it became much more natural and much more intuitive," said Jaimie Henderson, a Stanford neurosurgeon who is a part of BrainGate and is the new paper's lead author.

In this clip, T7 steers the cursor among eight radial targets. Both test subjects were able to perform these tasks in less than half the time it took a previous participant. "Both of the participants found the system relatively easy to use," Henderson said.

These experiments are designed to make computers accessible to the disabled. But "we're not only interested in computer cursor control," Henderson said. BrainGate will apply its findings to the development of robotic limbs and ways to reconnect brain and muscle—"all sorts of functional restorations using the signals we decode from the brain."