Scientists at the University of Chicago have shown that it is possible to implant brain-computer interfaces and let amputees control robotic arms, even years after their amputations. Similar research has previously focused on paralyzed people and whether they can benefit from technology that lets them move external devices by simply willing and thinking of wanted movements. The new development extends a great deal of this research to amputees.
In the latest study, the subjects were three rhesus monkeys that lost their limbs in accidents between four and ten years prior. Two of the monkeys had electrodes placed at the motor cortex on the side of the brain that is in charge of the amputated limb, while the third monkey had the electrodes placed on the opposite side, which still controlled the intact limb. The electrodes were connected to a computer that in turn moved a robotic arm. Following, the three monkeys were trained to move the robotic arm through conscious thought while the implanted electrodes monitored neuronal activity.
The monkeys did indeed manage to become proficient with their robotic arms, but that’s not the end of the research findings. What was particularly welcome was that the neural connections within the part of the brain that should be controlling the amputated limb grew significantly both in density and signal strength. The third monkey, who had the implants placed on the side that controlled the existing arm, first had a sharp drop in neuronal activity and connection density that later rebounded and returned to a seemingly more normal state.
All this demonstrates that the brain is incredibly adaptive and neuroplasticity can be harnessed to help restore lost function and train brain regions to perform tasks they were never intended to perform.
Comparison of network density between the contralateral and ipsilateral monkeys. When using the brain machine interface, the contralateral monkey showed a steady increase in the network connectivity. On the contrary, the ipsilateral monkey showed an initial pruning before having a steady increase in the network density. Each node in the diagram corresponds to a neuron (R – reach and G – grasp neurons).
Study in Nature Communications: Changes in cortical network connectivity with long-term brain-machine interface exposure after chronic amputation…
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