Tropes

www.electronicsweekly.com 2015 03593.txt.txt

#Robot arm controlled by quadriplegic intentions Californian researchers have linked a robot arm to the brain of a quadriplegic man, giving him smooth control over the arm. The electrodes are not in the motor cortex or attached to muscle nerves, but are in a part of the brain associated with planning muscle activity: the posterior parietal cortex, or PPC. hen you move your arm, you really don think about which muscles to activate and the details of the movement such as lift the arm, extend the arm, grasp the cup, close the hand around the cup, and so on. Instead, you think about the goal of the movement want to pick up that cup of water, for example, said Caltec professor Richard Andersen. o in this trial, we were able to decode these actual intents, by asking the subject to simply imagine the movement as a whole, rather than breaking it down into myriad components. Caltec team shared the research with scientist from the University of Southern California. According to Caltech the process of recognising a person and then shaking hands begins with a visual signal that is first processed in the lower visual areas of the cerebral cortex. The signal then moves up to the PPC, a high-level cognitive area where the initial intent to make a movement is formed. These intentions are transmitted to the motor cortex, on through the spinal cord, and then to the muscles where movement is executed. Implanting electrodes in the PPC, with appropriate computer processing, has given the patient he ability to perform a fluid handshaking gesture and even play ock, paper, scissorsusing a robotic arm, said Caltec. The patent, Eric Sorto, was shot in the neck more than a decade ago. Two arrays each of 96 micro-electrodes were implanted into his PPC in 2013. Functional magnetic resonance imaging his neurons to be monitored while Sorto imagined various types of limb and eye movements. Based on the recorded neural activity it became possible for researchers to predict which limbs he wanted to move, where he wanted to move them, when, and how fast. This information was used then to steer a computer cursor or to direct a robotic arm the latter developed by Johns hopkins university. Beyond this it was found that Sorto could alter the activity of neuron populations simply by imagining different motor actions. Trying to control the limb directly with thoughts like should move my hand over toward to the object in a certain waydidn work, while want to grasp the object, was more likely to succeed. Visual feedback allows Sorto to control large movements, but touch feedback is needed for fine control, ithout touch, it like going to the dentist and having your mouth numbed. It very hard to speak without somatosensory feedback, said Andersen whose team is working on a mechanism to relay signals from the robotic arm back into the part of the brain that gives the perception of touch

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