Images by Hajime Sorayama .
The patient lost the use of a her limbs over a decade previously to a degenerative disease that caused damage to her spinal cord. The resulting disruption to her nervous system left her bed bound and unable to do anything for herself. Doctors requested that the women test a revolutionary robotic arm that is controlled indirectly by the patient’s brain.
The robotic arm is connected to an intuitive computer program that interprets natural brain function and activity focussed on moving our limbs and utilises them to control the robotic arm. This is the first device of its kind with truly successful neurobiological interface. Several other groups around the world are experimenting with this technology, but these doctors are the first to appropriate the technology to be advantageous in a medical environment.
“At the end of a good day, when she was making these beautiful movements, she was ecstatic…that was nice to see,” said Andrew Schwartz, professor of neurobiology at the university. The prosthetic arm follows the laws of natural movement and emulates human movement and control; it can move directionally, positionally and it can be used to lift and pick up objects. Proficiency with the robotic arm requires training, although it only took the patient a matter of weeks to acquire full control of the prosthetic.
This is by no means a simple procedure, though, with connection to the arm requiring major surgery. In a four hour procedure, doctors implanted two 4mm microelectrode arrays into the left motor cortex beneath the surface of the patient’s brain, where tiny electrodes directly detect neuron signals emitted by the brain. Wires from the electrodes run to connectors, which are attached to the patient’s head, which doctors use to attach the patient to the computer program. Amplified brain signals are processed by the program’s brain-machine interface, which then passes the brain signals as commands to the arm, which operates in real time.
Doctors recorded and mapped electrical activity from individual neurons in the patient’s brain whilst she imagined various arm and hand movements. Neurons that control movement have a proclivity to move preferentially, and once the neurons are activated during the imagination of specific movements, doctors are able to program the arm to imitate the patient’s required movement. The results of this particular patient were staggering: after a short period, the patient was able to complete over 91.6% of tasks assigned to her and even gained an increase in the speed of operation.
Although this is a significant break-through and certainly an applaudable bio-medical achievement, there are difficulties to overcome before the technology can be made available to more patients. The electrodes implanted into the patient’s brain have been causing scar tissue to form, which degrades the amplification of the brain signals the program interprets. Moreover, although researchers are already intending to progress the technology into the realms of sense (this involves attaching the mircoelectrodes to the sensory regions of the brain), it is still only available for patients that can be plugged into a computer to control and power the robotic arm.
Despite these minor drawbacks, unlocking this technology has enabled doctors to make incredible advancements in neurobiology and neuroscience that could one day benefit any person with a deficient or missing limb. Imagine every amputee provided the opportunity to have a mechanical limb directly controlled by their brain, without the use of a computer. That’s an idea to strive for.