Monday, October 10, 2011

Man controls robot arm with his mind

A paraplegic man was able to control a mechanic arm using only his brain, paving the way for true robotic limbs that we can control as if they were our own. This was achieved by connecting electrodes in a chip to brain parts that normally control muscles. Because the brain output is wired through the electrodes, thoughts about movement can be translated into actual movement by the robotic arm. The hard part is, of course, to 'read' what the brain wants and turn that into movement that reflects what the patient thought. While we are able to determine, by imaging techniques, what brain area is used for specific thoughts, actually using the output as input for a mechanical device is new. Because the man with the brain chip was able to grab a ball and consequently let it go, the device seems to be suitable for complex movement.

The robot arm was tested on a patient that is paralyzed from the neck down, which renders all motoric behaviour impossible: the brain is connected to the rest of the body by the spinal cord, that conveys all  neuronal signals. Because these are blocked, scientists need to tap into the brain directly to get the required brain signals that instruct movement. These signals are acquired by a chip that is implanted into the brain, and works by measuring groups of cells of which their function is more or less known: before the chip was implanted, the patient was put into a scanner and was told to imagine arm movement. This activates the same brain areas as in normal movement, which allowed the scientists to see where they had to place the chip to obtain the correct readings.

One of the advantages of this novel chip, is that it is less invasive than previous versions, that needed to be placed deep inside the brain to read the necessary signals. This reduces the chance that the immune system will eventually destroy the electrodes, rendering the device dysfunctional.

Previous versions of a brain chip required connection to a computer, that made movement of a robot arm possible. The small chip, with the size of only two stamps, seems a step forward in creating a true human-computer-interface, able to artificially restore functionality of limbs.

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