Using the mind to control prosthetic limbs is a bold idea that is slowly becoming a reality thanks to several important advances in neuroscience and robotics in the last couple of years. Now a team of researchers is claiming another significant breakthrough in this area, building a prosthetic arm whose individual fingers can be controlled via the mind, right down to the pinkie.

We've seen a number of mind-controlled prosthetics aimed at allowing amputees to better carry out complex tasks. These have included bionic hands that grasp objects, allow paralyzed patients to feel a sense of touch and even systems that allow for control of two prosthetic arms at once.

Now researchers at John Hopkins University have built a prosthetic they claim offers something those to come before it don't: the ability to control fingers independently of one another using the mind. The team worked with a male subject who was not missing an arm, but had epilepsy, and was therefore already set to undergo brain mapping to determine the origin of his seizures.

The neurosurgeon implanted an array of 128 electrodes over the part of the brain controlling hand and arm movements. The researchers then instructed the subject to move individual fingers, while using a purpose-made computer program to monitor which parts of the brain emitted an electric signal as he did.

The team then turned its attention to measuring electrical brain activity involved in tactile sensation by fitting the man with a glove that had been equipped with small vibrators on the fingertips. They then buzzed each finger individually and recorded the electrical signals that were coming from the brain.

Armed with this motory and sensory data, the team then programmed the prosthetic arm to move its fingers depending on which part of the brain was lighting up. They wired the prosthetic up to the electrodes in the patient's brain and instructed him to think about moving each of his fingers, finding that the electrical signals were enough to trigger the movement of the corresponding prosthetic fingers.

At first, the limb was able to be controlled via thought with 76 percent accuracy, but the researchers were able to boost this to 88 percent by grouping the ring and pinkie fingers together. They say that the part of the brain that controls these two fingers overlaps and people generally move them together anyway, so the increased accuracy was to be expected.

While the proof-of-concept system is a promising development that brings the prospect of restoring finer hand function to amputees, the researchers note that real world application of the technology is still years away and will be expensive, involving much brain mapping and computer programming.

You can see a demonstration of the mind-controlled finger movement in the video below. The research was published in the Journal of Neural Engineering.

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