Solutions from Science Fiction: Brain Machine Interfaces and Prosthetics

by Olivia Woodford-Berry '19

      For most people, brain machine interfaces (BMI) seem like something out of a science fiction movie. For Nathan Copeland, these technologies are the breakthrough he has been waiting for. Copeland, who has been paralyzed from the upper-chest down since an accident in 2004, is one of the first people to be fitted with a direct brain interface, a system of electrodes surgically implanted into his brain and externally connected to a computer system. Through a new robotic prosthetic, Nathan has not only regained a functioning arm, but also his sense of touch.
         The intersection of brain machine interfaces and prosthetics has come to fruition through research funded by the U.S. Department of Defense. The Defense Advanced Research Projects Agency (DARPA), a department branch focused on developing technologies, originally began research in BMI with the hopes of finding applications in aerospace or defense [1]. In 2006, DARPA shifted their focus and launched their Revolutionizing Prosthetics Program. This program has created a huge push to redefine the parameters of prosthetics and the use to robotics in medical treatments [2].
           With funding from this program, researchers developed robotic limbs with motor capabilities through the linking of neural mapping technologies and robotics. Neurologists map which areas of the brain are active in initiating and controlling specific functions. Working in parallel with computer scientists, they can apply this information to create BMI prosthetics. In initial trials, voluntary participants underwent surgery to implant microelectrode arrays into their primary motor cortex, the part of the brain that controls movement. These electrodes pick up biological cues from the brain relay them through wires to an attached computer system. This computer system translates chemical signals into mechanical commands, which are than relayed to and executed by a robotic arm [3][4].

      In addition, researchers have successively reverse engineered these designs in order to send sensory information from the robotics back to the user (see video). By connecting similar electrodes to the primary somatosensory cortex of the brain, trial participants, like Copeland, can now recognize when and where pressure is applied to device sensors with striking accuracy [5].  The resulting prototypes allow participant to control the prosthetic with near natural ease. They have essentially created a robotic upper-body prosthetic that circumvents the spinal cord as a biological messenger. Thus, there is a new path to mobility and sensation for paralysis patients. 

      Although these technologies are still in the research phase, DARPA scientists hope to improve these designs and to eventually make them accessible to millions.  Researchers plan to continue mapping sensory neural pathways and to eventually extend the sensory capacities of robotic limbs beyond pressure sensing.  Along the same lines, DARPA is launching the Hand Proprioception and Touch Interfaces (HAPTIX) Program with the goal of creating an alternative structure that incorporates the peripheral nervous system into the passage of information between the brain and the prosthetic [6][7]. This has the potential to broaden the market from those with spinal cord injuries looking for mobility to amputees drawn to the sensory functions. Furthermore, utilizing the nervous system may cut out bulky computer systems, allowing for a more marketable product. DARPA hopes to create an FDA approved design for this system by 2019 [4].

Sources:
[1] http://www.darpa.mil/our-research
[2] http://www.darpa.mil/program/revolutionizing-prosthetics
[3] http://www.jhuapl.edu/prosthetics/program/default.asp
[4] http://www.darpa.mil/news-events/2016-10-13
[5] Flesher SF, Collinger JL, Foldes ST, Weiss JM, Downey JE, Tyler-Kabara EC, Bensmaia SJ, Schwartz AB, Boninger ML, Guant RA. Intracortical Microstimulation of Human Somatosensory Cortex. Sci. Transl. Med. 2016 Oct. 19;8(361):361-341.141-51.
[6] http://www.darpa.mil/program/our-research/darpa-and-the-brain-initiative
[7] http://www.darpa.mil/program/hand-proprioception-and-touch-interfaces