Brain-Controlled Prosthetics in Future

Researchers are making tremendous progress in developing artificial limbs that can be controlled by the brain activity of people wearing those limbs. These devices utilize what is known as a "brain-computer interface" (BCI), of which there are two varieties: An individual's neuronal activity measurements can be detected using "single-unit recording", in which each electrode is implanted adjacent to an individual brain cell. Alternatively, the brain activity can be measured using electroencephalography (EEG), in which electrodes are attached to the patient's scalp, to measure aggregate signals.

It is expected that within a few years, these neural-controlled prosthetics will allow amputees, paraplegics, and people paralyzed by neurodegenerative diseases to regain movement of their artificial limbs or nonfunctioning natural limbs, and thus increase their ability to communicate with others, care for themselves, and engage in basic movement and activities that most of us take for granted.

Examples of progress in this field are cropping up everywhere. In Sweden, scientists have significantly refined the functioning of a prosthetic hand, using BCI technology. At the University of Pittsburgh, researchers are creating a new anthropomorphic robotic arm.

There are, however, some downsides to each of the two BCI methods mentioned above. In the case of single-unit recording, surgically implanted electrodes carry the risk of infection within the brain. Also, the quality of the signals detected can deteriorate as a result of neural scarring around the electrodes — scarring that builds up over time. In the case of EEG recording, the signal measured is much fuzzier, making corrected interpretation of the data that much more difficult. Moreover, patients need to receive extensive training in order to master controlling their artificial limbs using thought patterns.

Fortunately, researchers are already coming up with several new approaches that could reduce the drawbacks of the two pioneering methods. Scientists at the Wadsworth Center of the New York State Department of Health, joining forces with colleagues at the Washington University in St. Louis, are trying a new technique of recording from the surface of the brain, inside the skull. This new approach, electrocorticographic (ECoG) recording, has the advantage that the electrodes do not have to penetrate the patient's brain.

This method has already been shown to work in a limited form, by Gerwin Schalk, MS, a computer scientist at the Wadsworth Center and leader of this effort. His team's tests demonstrated that humans can use ECoG recording to move a cursor on a computer screen, at least along one dimension. They are presently attempting to extend the study to see if humans can control motion in two dimensions. It should be noted that the patient involved in the experiment did not have to undergo unneeded surgery, because the individual was about to undergo therapeutic brain surgery for epilepsy anyway.

Another approach showing promise is being developed in the laboratory of Richard Andersen, Ph.D., at the California Institute of Technology. His team has come up with a method that records local field potentials (LFPs), which detects neural activity in hundreds of thousands of brain cells near each electrode, rather than detecting the activity of an individual cell. This reduces the fuzziness of the data gathered, and leverages the way that human thought employs areas within the cortex, and not just single brain cells.

These encouraging steps forward are being reported to the public by The Society for Neuroscience and other groups devoted to increasing mankind's understanding of how the brain and nervous system works, as well as how that new knowledge can be utilized to create man-machine interfaces that we could only dream about decades ago.

Yet there is one extremely disturbing aspect to these developments, not mentioned by any of the medical press sources consulted for writing this article. If neural detection technology advances to the point where outside observers can detect and properly interpret electromagnetic signals given off by an individual's thinking, then someday in the distant future we may reach a nightmare scenario in which governments could mandate that all citizens wear EEG-enabled skullcaps that record and transmit to officials the ongoing brain activity of the wearer, so that government officials could continuously monitor our thoughts. This would undoubtedly be done in the name of "homeland security".